Apparatus for transmitting broadcast signals, apparatus for receiving broadcast signals, method for transmitting broadcast signals and method for receiving broadcast signals

ABSTRACT

Disclosed herein is a method for sending a broadcast signal. The method includes formatting input streams into multiple data pipes (DPs). Formatting the input streams into the multiple DPs includes splitting the input streams into multiple data streams, deleting a null packet included in a data stream, and forming a baseband frame (BBF) by adding a header to the data stream. The baseband frame includes a deleted null packet (DNP) field indicative of the number of deleted null packets, and the DNP field comprises at least one of a first DNP or a second DNP.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Provisional Application No.61/903,399 filed on 13 Nov, 2013 in US, and Provisional Application No.61/908,169 filed on 24 Nov, 2014 in US the entire contents of which ishereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for transmitting broadcastsignals, an apparatus for receiving broadcast signals and methods fortransmitting and receiving broadcast signals.

2. Related Art

As analog broadcast signal transmission comes to an end, varioustechnologies for transmitting/receiving digital broadcast signals arebeing developed. A digital broadcast signal may include a larger amountof video/audio data than an analog broadcast signal and further includevarious types of additional data in addition to the video/audio data.

That is, a digital broadcast system can provide HD (high definition)images, multi-channel audio and various additional services. However,data transmission efficiency for transmission of large amounts of data,robustness of transmission/reception networks and network flexibility inconsideration of mobile reception equipment need to be improved fordigital broadcast.

SUMMARY OF THE INVENTION

The present invention provides a method of newly defining a deleted nullpacket indicator (DNPI) and inserting a deleted null packet (DNP) onlywhen a null packet is present in order to solve a problem in that a DNPis inserted irrespective of whether a null packet is present or not.

Furthermore, the present invention provides a method of newly defining aDNP structure of a 2-byte size and deleting a null packet in order toreduce overhead attributable to the transmission of unnecessary nullpackets.

Technical objects to be achieved by this specification are not limitedto the aforementioned objects, and other technical objects that have notbeen described above will be evidently understood by those skilled inthe art to which the present invention pertains from the followingdescription.

In an aspect, there is provided a method for sending a broadcast signal.The method includes formatting at least one input stream into at leastone data pipe (DP), encoding the data of the at least one DP for eachDP, generating at least one signal frame by mapping the encoded data,and modulating the data of the generated signal frame using anorthogonal frequency division multiplexing (OFDM) scheme and sending abroadcast signal including the modulated data of the signal frame.Formatting the at least one input stream into the at least one DPincludes splitting the at least one input stream into at least one datastream, deleting at least one null packet included in the at least onedata stream, and forming a baseband frame (BBF) by adding a header tothe at least one data stream. The baseband frame includes at least onedeleted null packet (DNP) field indicative of the number of deleted nullpackets, and the at least one DNP field includes at least one of a firstDNP and a second DNP.

Furthermore, in the present invention, deleting the at least one nullpacket includes checking whether the at least one null packet is presentor not, deleting the at least one null packet if the at least one nullpacket is found to be present, counting the number of deleted nullpackets, and inserting a deleted null packet (DNP) field into a locationfrom which the at least one null packet has been deleted.

Furthermore, in the present invention, the DNP field inserted into thelocation from which the at least one null packet has been deleted is setas the counted value.

Furthermore, in the present invention, the at least one data streamincludes a deleted null packet indicator (DNPI) field indicative ofwhether or not a next packet is a null packet.

Furthermore, in the present invention, if the DNPI field is set as avalue indicating that a next packet is a null packet, the DNP field isinserted into a data packet subsequent to a data packet including theDNPI field.

Furthermore, in the present invention, the header of the at least onedata packet is generated by compressing a packet identifier (PID) ordeleting the PID.

Furthermore, in the present invention, the DNP field has a size of 2bytes, and each of the first DNP and the second DNP has a size of 1byte.

Furthermore, in the present invention, the DNP field includes only thefirst DNP if the number of deleted null packets is a specific number orless, and the DNP field includes the first DNP and the second DNP if thenumber of deleted null packets is a specific number or more.

Furthermore, in the present invention, the first DNP is set as aspecific value indicative of a specific number of null packets if thefirst DNP and the second DNP are included in the DNP field, and thesecond DNP is set as a value obtained by subtracting the value of thefirst DNP from a total number of deleted null packets.

Furthermore, in the present invention, the second DNP is placed next tothe first DNP.

Furthermore, in the present invention, the data stream includes aservice or service component stream.

Furthermore, in the present invention, the at least one data streamincludes at least one of at least one data packet and at least one nullpacket, and the DNPI field is included in the header of the at least onedata packet.

Furthermore, in another aspect, there is provided a transmissionapparatus for sending a broadcast signal. The transmission apparatusincludes an input formatting module configured to format at least oneinput stream into at least one data pipe (DP), a bit interleaved codingand modulation (BICM) module configured to encode the data of the atleast one DP for each DP, a frame building module configured to generateat least one signal frame by mapping the encoded data, and an orthogonalfrequency division multiplexing (OFDM) generation module configured tomodulate the data of the generated signal frame using an OFDM scheme andsend a broadcast signal including the modulated data of the signalframe. The input formatting module includes an input stream splittermodule configured to split the at least one input stream into at leastone data stream, a null packet deletion module configured to delete atleast one null packet included in the at least one data stream, and a BBframe header insertion module configured to form a baseband frame (BBF)by adding a header to the at least one data stream. The baseband frameincludes at least one deleted null packet (DNP) field indicative of thenumber of deleted null packets, and the at least one DNP field includesat least one of a first DNP and a second DNP.

Furthermore, in the present invention, the null packet deletion moduleincludes a null packet check module configured to check whether the atleast one null packet is present or not, a null packet processing moduleconfigured to delete the at least one null packet and count the numberof deleted null packets, and a DNP insertion module configured to inserta deleted null packet (DNP) field into a location from which the atleast one null packet has been deleted.

Furthermore, in the present invention, the null packet processing moduleincludes a null packet deletion module configured to delete the at leastone null packet if the at least one null packet is found to be presentand a null packet counter module configured to count the number ofdeleted null packets.

Furthermore, in the present invention, the at least one data streamincludes at least one of at least one data packet and at least one nullpacket, and a header of the at least one data packet includes a deletednull packet indicator (DNPI) field indicative of whether a next packetis a null packet.

Furthermore, in the present invention, the input stream is a transportstream (TS) stream.

Furthermore, in another aspect, there is provided a receiving apparatusfor receiving a broadcast signal. The receiving apparatus includes ademapping and decoding module; and an output processor module restoringmultiple data pipes output from the demapping and decoding module toinput streams, wherein the output processor module includes a basebandframe processor block decoding information transmitted to a header of abaseband frame and restoring the input streams by using the decodedinformation, wherein the baseband frame comprises a deleted null packet(DNP) field indicative of a number of deleted null packets, and whereinthe DNP field comprises at least one of a first DNP or a second DNP.

This specification is advantageous in that overhead in the transmissionof a data stream can be reduced by newly defining a deleted null packetindicator (DNPI) indicative of whether a null packet is present or notand inserting a DNP only when a null packet is present.

Furthermore, the present invention is advantageous in that overheadattributable to the transmission of unnecessary null packets can bereduced by representing the number of null packets through a DNPstructure of a 2-byte size.

Advantages that may be achieved by the present invention are not limitedto the aforementioned advantages, and those skilled in the art to whichthe present invention pertains will readily appreciate other advantagesthat have not been described from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention;

FIG. 2 illustrates an input formatting block according to one embodimentof the present invention;

FIG. 3 illustrates an input formatting block according to anotherembodiment of the present invention;

FIG. 4 illustrates an input formatting block according to anotherembodiment of the present invention;

FIG. 5 illustrates a BICM block according to an embodiment of thepresent invention;

FIG. 6 illustrates a BICM block according to another embodiment of thepresent invention;

FIG. 7 illustrates a frame building block according to one embodiment ofthe present invention;

FIG. 8 illustrates an OFMD generation block according to an embodimentof the present invention;

FIG. 9 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention;

FIG. 10 illustrates a frame structure according to an embodiment of thepresent invention;

FIG. 11 illustrates a signaling hierarchy structure of the frameaccording to an embodiment of the present invention;

FIG. 12 illustrates preamble signaling data according to an embodimentof the present invention;

FIG. 13 illustrates PLS1 data according to an embodiment of the presentinvention;

FIG. 14 illustrates PLS2 data according to an embodiment of the presentinvention;

FIG. 15 illustrates PLS2 data according to another embodiment of thepresent invention;

FIG. 16 illustrates a logical structure of a frame according to anembodiment of the present invention;

FIG. 17 illustrates PLS mapping according to an embodiment of thepresent invention;

FIG. 18 illustrates EAC mapping according to an embodiment of thepresent invention;

FIG. 19 illustrates FIC mapping according to an embodiment of thepresent invention;

FIG. 20 illustrates a type of DP according to an embodiment of thepresent invention;

FIG. 21 illustrates DP mapping according to an embodiment of the presentinvention;

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention;

FIG. 23 illustrates a bit interleaving according to an embodiment of thepresent invention;

FIG. 24 illustrates a cell-word demultiplexing according to anembodiment of the present invention;

FIG. 25 illustrates a time interleaving according to an embodiment ofthe present invention;

FIG. 26 is a diagram illustrating an example of the mode adaptationmodule of a transmission apparatus to which proposed methods may beapplied;

FIG. 27 is a diagram illustrating an example of the mode adaptationmodule of a reception apparatus proposed by the present invention;

FIG. 28 is a diagram illustrating an example of a conventional TS packetheader format;

FIG. 29 is a diagram illustrating an example of a conventional method ofdeleting null packets;

FIG. 30 is a diagram illustrating an example of the format of a TSpacket header proposed by the present invention;

FIG. 31 is a diagram illustrating another example of the format of a TSpacket header proposed by the present invention;

FIG. 32 is a diagram illustrating yet another example of the format of aTS packet header proposed by the present invention;

FIG. 33 is a diagram illustrating an example of a method of deletingnull packets using the DNPI field of FIGS. 30 to 32;

FIG. 34 is a diagram illustrating an example of a conventional DNPstructure;

FIG. 35 illustrates an example of a DNP structure proposed by thepresent invention; and

FIG. 36 is a diagram illustrating an example of a method of deletingnull packets using the DNP structure of FIG. 35.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The detailed description, which will be given below withreference to the accompanying drawings, is intended to explain exemplaryembodiments of the present invention, rather than to show the onlyembodiments that can be implemented according to the present invention.The following detailed description includes specific details in order toprovide a thorough understanding of the present invention. However, itwill be apparent to those skilled in the art that the present inventionmay be practiced without such specific details.

Although most terms used in the present invention have been selectedfrom general ones widely used in the art, some terms have beenarbitrarily selected by the applicant and their meanings are explainedin detail in the following description as needed. Thus, the presentinvention should be understood based upon the intended meanings of theterms rather than their simple names or meanings.

The present invention provides apparatuses and methods for transmittingand receiving broadcast signals for future broadcast services. Futurebroadcast services according to an embodiment of the present inventioninclude a terrestrial broadcast service, a mobile broadcast service, aUHDTV service, etc. The present invention may process broadcast signalsfor the future broadcast services through non-MIMO (Multiple InputMultiple Output) or MIMO according to one embodiment. A non-MIMO schemeaccording to an embodiment of the present invention may include a MISO(Multiple Input Single Output) scheme, a SISO (Single Input SingleOutput) scheme, etc.

While MISO or MIMO uses two antennas in the following for convenience ofdescription, the present invention is applicable to systems using two ormore antennas.

The present invention may defines three physical layer (PL)profiles-base, handheld and advanced profiles-each optimized to minimizereceiver complexity while attaining the performance required for aparticular use case. The physical layer (PHY) profiles are subsets ofall configurations that a corresponding receiver should implement.

The three PHY profiles share most of the functional blocks but differslightly in specific blocks and/or parameters. Additional PHY profilescan be defined in the future. For the system evolution, future profilescan also be multiplexed with the existing profiles in a single RFchannel through a future extension frame (FEF). The details of each PHYprofile are described below.

1. Base Profile

The base profile represents a main use case for fixed receiving devicesthat are usually connected to a roof-top antenna. The base profile alsoincludes portable devices that could be transported to a place butbelong to a relatively stationary reception category. Use of the baseprofile could be extended to handheld devices or even vehicular by someimproved implementations, but those use cases are not expected for thebase profile receiver operation.

Target SNR range of reception is from approximately 10 to 20 dB, whichincludes the 15 dB SNR reception capability of the existing broadcastsystem (e.g. ATSC A/53). The receiver complexity and power consumptionis not as critical as in the battery-operated handheld devices, whichwill use the handheld profile. Key system parameters for the baseprofile are listed in below table 1.

TABLE 1 LDPC codeword length 16K, 64K bits Constellation size 4~10 bpcu(bits per channel use) Time de-interleaving memory ≦2¹⁹ data cells sizePilot patterns Pilot pattern for fixed reception FFT size 16K, 32Kpoints

2. Handheld Profile

The handheld profile is designed for use in handheld and vehiculardevices that operate with battery power. The devices can be moving withpedestrian or vehicle speed. The power consumption as well as thereceiver complexity is very important for the implementation of thedevices of the handheld profile. The target SNR range of the handheldprofile is approximately 0 to 10 dB, but can be configured to reachbelow 0 dB when intended for deeper indoor reception.

In addition to low SNR capability, resilience to the Doppler Effectcaused by receiver mobility is the most important performance attributeof the handheld profile. Key system parameters for the handheld profileare listed in the below table 2.

TABLE 2 LDPC codeword length 16K bits Constellation size 2~8 bpcu Timede-interleaving memory ≦2¹⁸ data cells size Pilot patterns Pilotpatterns for mobile and indoor reception FFT size 8K, 16K points

3. Advanced Profile

The advanced profile provides highest channel capacity at the cost ofmore implementation complexity. This profile requires using MIMOtransmission and reception, and UHDTV service is a target use case forwhich this profile is specifically designed. The increased capacity canalso be used to allow an increased number of services in a givenbandwidth, e.g., multiple SDTV or HDTV services.

The target SNR range of the advanced profile is approximately 20 to 30dB. MIMO transmission may initially use existing elliptically-polarizedtransmission equipment, with extension to full-power cross-polarizedtransmission in the future. Key system parameters for the advancedprofile are listed in below table 3.

TABLE 3 LDPC codeword length 16K, 64K bits Constellation size 8~12 bpcuTime de-interleaving memory ≦2¹⁹ data cells size Pilot patterns Pilotpattern for fixed reception FFT size 16K, 32K points

In this case, the base profile can be used as a profile for both theterrestrial broadcast service and the mobile broadcast service. That is,the base profile can be used to define a concept of a profile whichincludes the mobile profile. Also, the advanced profile can be dividedadvanced profile for a base profile with MIMO and advanced profile for ahandheld profile with MIMO. Moreover, the three profiles can be changedaccording to intention of the designer.

The following terms and definitions may apply to the present invention.The following terms and definitions can be changed according to design.

auxiliary stream: sequence of cells carrying data of as yet undefinedmodulation and coding, which may be used for future extensions or asrequired by broadcasters or network operators

base data pipe: data pipe that carries service signaling data

baseband frame (or BBFRAME): set of Kbch bits which form the input toone FEC encoding process (BCH and LDPC encoding)

cell: modulation value that is carried by one carrier of the OFDMtransmission

coded block: LDPC-encoded block of PLS1 data or one of the LDPC-encodedblocks of PLS2 data

data pipe: logical channel in the physical layer that carries servicedata or related metadata, which may carry one or multiple service(s) orservice component(s).

data pipe unit: a basic unit for allocating data cells to a DP in aframe.

data symbol: OFDM symbol in a frame which is not a preamble symbol (theframe signaling symbol and frame edge symbol is included in the datasymbol)

DP_ID: this 8-bit field identifies uniquely a DP within the systemidentified by the SYSTEM_ID

dummy cell: cell carrying a pseudo-random value used to fill theremaining capacity not used for PLS signaling, DPs or auxiliary streams

emergency alert channel: part of a frame that carries EAS informationdata

frame: physical layer time slot that starts with a preamble and endswith a frame edge symbol

frame repetition unit: a set of frames belonging to same or differentphysical layer profile including a FEF, which is repeated eight times ina super-frame

fast information channel: a logical channel in a frame that carries themapping information between a service and the corresponding base DP

FECBLOCK: set of LDPC-encoded bits of a DP data

FFT size: nominal FFT size used for a particular mode, equal to theactive symbol period Is expressed in cycles of the elementary period T

frame signaling symbol: OFDM symbol with higher pilot density used atthe start of a frame in certain combinations of FFT size, guard intervaland scattered pilot pattern, which carries a part of the PLS data

frame edge symbol: OFDM symbol with higher pilot density used at the endof a frame in certain combinations of FFT size, guard interval andscattered pilot pattern

frame-group: the set of all the frames having the same PHY profile typein a super-frame.

future extension frame: physical layer time slot within the super-framethat could be used for future extension, which starts with a preamble

Futurecast UTB system: proposed physical layer broadcasting system, ofwhich the input is one or more MPEG2-TS or IP or general stream(s) andof which the output is an RF signal

input stream: A stream of data for an ensemble of services delivered tothe end users by the system.

normal data symbol: data symbol excluding the frame signaling symbol andthe frame edge symbol

PHY profile: subset of all configurations that a corresponding receivershould implement

PLS: physical layer signaling data consisting of PLS1 and PLS2

PLS1: a first set of PLS data carried in the FSS symbols having a fixedsize, coding and modulation, which carries basic information about thesystem as well as the parameters needed to decode the PLS2

NOTE: PLS1 data remains constant for the duration of a frame-group.

PLS2: a second set of PLS data transmitted in the FSS symbol, whichcarries more detailed PLS data about the system and the DPs

PLS2 dynamic data: PLS2 data that may dynamically change frame-by-frame

PLS2 static data: PLS2 data that remains static for the duration of aframe-group

preamble signaling data: signaling data carried by the preamble symboland used to identify the basic mode of the system

preamble symbol: fixed-length pilot symbol that carries basic PLS dataand is located in the beginning of a frame

NOTE: The preamble symbol is mainly used for fast initial band scan todetect the system signal, its timing, frequency offset, and FFT-size.

reserved for future use: not defined by the present document but may bedefined in future

super-frame: set of eight frame repetition units

time interleaving block (TI block): set of cells within which timeinterleaving is carried out, corresponding to one use of the timeinterleaver memory

TI group: unit over which dynamic capacity allocation for a particularDP is carried out, made up of an integer, dynamically varying number ofXFECBLOCKs

NOTE: The TI group may be mapped directly to one frame or may be mappedto multiple frames. It may contain one or more TI blocks.

Type 1 DP: DP of a frame where all DPs are mapped into the frame in TDMfashion

Type 2 DP: DP of a frame where all DPs are mapped into the frame in FDMfashion

XFECBLOCK: set of Ncells cells carrying all the bits of one LDPCFECBLOCK

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

The apparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can includean input formatting block 1000, a BICM (Bit interleaved coding &modulation) block 1010, a frame structure block 1020, an OFDM(Orthogonal Frequency Division Multiplexing) generation block 1030 and asignaling generation block 1040. A description will be given of theoperation of each module of the apparatus for transmitting broadcastsignals.

IP stream/packets and MPEG2-TS are the main input formats, other streamtypes are handled as General Streams. In addition to these data inputs,Management Information is input to control the scheduling and allocationof the corresponding bandwidth for each input stream. One or multiple TSstream(s), IP stream(s) and/or General Stream(s) inputs aresimultaneously allowed.

The input formatting block 1000 can demultiplex each input stream intoone or multiple data pipe(s), to each of which an independent coding andmodulation is applied. The data pipe (DP) is the basic unit forrobustness control, thereby affecting quality-of-service (QoS). One ormultiple service(s) or service component(s) can be carried by a singleDP. Details of operations of the input formatting block 1000 will bedescribed later.

The data pipe is a logical channel in the physical layer that carriesservice data or related metadata, which may carry one or multipleservice(s) or service component(s).

Also, the data pipe unit: a basic unit for allocating data cells to a DPin a frame.

In the BICM block 1010, parity data is added for error correction andthe encoded bit streams are mapped to complex-value constellationsymbols. The symbols are interleaved across a specific interleavingdepth that is used for the corresponding DP. For the advanced profile,MIMO encoding is performed in the BICM block 1010 and the additionaldata path is added at the output for MIMO transmission. Details ofoperations of the BICM block 1010 will be described later.

The Frame Building block 1020 can map the data cells of the input DPsinto the OFDM symbols within a frame. After mapping, the frequencyinterleaving is used for frequency-domain diversity, especially tocombat frequency-selective fading channels. Details of operations of theFrame Building block 1020 will be described later.

After inserting a preamble at the beginning of each frame, the OFDMGeneration block 1030 can apply conventional OFDM modulation having acyclic prefix as guard interval. For antenna space diversity, adistributed MISO scheme is applied across the transmitters. In addition,a Peak-to-Average Power Reduction (PAPR) scheme is performed in the timedomain. For flexible network planning, this proposal provides a set ofvarious FFT sizes, guard interval lengths and corresponding pilotpatterns. Details of operations of the OFDM Generation block 1030 willbe described later.

The Signaling Generation block 1040 can create physical layer signalinginformation used for the operation of each functional block. Thissignaling information is also transmitted so that the services ofinterest are properly recovered at the receiver side. Details ofoperations of the Signaling Generation block 1040 will be describedlater.

FIGS. 2, 3 and 4 illustrate the input formatting block 1000 according toembodiments of the present invention. A description will be given ofeach figure.

FIG. 2 illustrates an input formatting block according to one embodimentof the present invention. FIG. 2 shows an input formatting module whenthe input signal is a single input stream.

The input formatting block illustrated in FIG. 2 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

The input to the physical layer may be composed of one or multiple datastreams. Each data stream is carried by one DP. Mode adaptation modulesslice an incoming data stream into data fields of the baseband frame(BBF). The system supports three types of input data streams: MPEG2-TS,Internet protocol (IP) and Generic stream (GS). MPEG2-TS ischaracterized by fixed length (188 byte) packets with the first bytebeing a sync-byte (0x47). An IP stream is composed of variable length IPdatagram packets, as signaled within IP packet headers. The systemsupports both IPv4 and IPv6 for the IP stream. GS may be composed ofvariable length packets or constant length packets, signaled withinencapsulation packet headers.

(a) shows a mode adaptation block 2000 and a stream adaptation 2010 forsignal DP and (b) shows a PLS generation block 2020 and a PLS scrambler2030 for generating and processing PLS data. A description will be givenof the operation of each block.

The Input Stream Splitter splits the input TS, IP, GS streams intomultiple service or service component (audio, video, etc.) streams. Themode adaptation module 2010 is comprised of a CRC Encoder, BB (baseband)Frame Slicer, and BB Frame Header Insertion block.

The CRC Encoder provides three kinds of CRC encoding for error detectionat the user packet (UP) level, i.e., CRC-8, CRC-16, and CRC-32. Thecomputed CRC bytes are appended after the UP. CRC-8 is used for TSstream and CRC-32 for IP stream. If the GS stream doesn't provide theCRC encoding, the proposed CRC encoding should be applied.

BB Frame Slicer maps the input into an internal logical-bit format. Thefirst received bit is defined to be the MSB. The BB Frame Slicerallocates a number of input bits equal to the available data fieldcapacity. To allocate a number of input bits equal to the BBF payload,the UP packet stream is sliced to fit the data field of BBF.

BB Frame Header Insertion block can insert fixed length BBF header of 2bytes is inserted in front of the BB Frame. The BBF header is composedof STUFFI (1 bit), SYNCD (13 bits), and RFU (2 bits). In addition to thefixed 2-Byte BBF header, BBF can have an extension field (1 or 3 bytes)at the end of the 2-byte BBF header.

The stream adaptation 2010 is comprised of stuffing insertion block andBB scrambler.

The stuffing insertion block can insert stuffing field into a payload ofa BB frame. If the input data to the stream adaptation is sufficient tofill a BB-Frame, STUFFI is set to ‘0’ and the BBF has no stuffing field.Otherwise STUFFI is set to ‘1’ and the stuffing field is insertedimmediately after the BBF header. The stuffing field comprises two bytesof the stuffing field header and a variable size of stuffing data.

The BB scrambler scrambles complete BBF for energy dispersal. Thescrambling sequence is synchronous with the BBF. The scrambling sequenceis generated by the feed-back shift register.

The PLS generation block 2020 can generate physical layer signaling(PLS) data. The PLS provides the receiver with a means to accessphysical layer DPs. The PLS data consists of PLS1 data and PLS2 data.

The PLS1 data is a first set of PLS data carried in the FSS symbols inthe frame having a fixed size, coding and modulation, which carriesbasic information about the system as well as the parameters needed todecode the PLS2 data. The PLS1 data provides basic transmissionparameters including parameters required to enable the reception anddecoding of the PLS2 data. Also, the PLS1 data remains constant for theduration of a frame-group.

The PLS2 data is a second set of PLS data transmitted in the FSS symbol,which carries more detailed PLS data about the system and the DPs. ThePLS2 contains parameters that provide sufficient information for thereceiver to decode the desired DP. The PLS2 signaling further consistsof two types of parameters, PLS2 Static data (PLS2-STAT data) and PLS2dynamic data (PLS2-DYN data). The PLS2 Static data is PLS2 data thatremains static for the duration of a frame-group and the PLS2 dynamicdata is PLS2 data that may dynamically change frame-by-frame.

The details of the PLS data will be described later.

The PLS scrambler 2030 can scramble the generated PLS data for energydispersal.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 3 illustrates an input formatting block according to anotherembodiment of the present invention.

The input formatting block illustrated in FIG. 3 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

FIG. 3 shows a mode adaptation block of the input formatting block whenthe input signal corresponds to multiple input streams.

The mode adaptation block of the input formatting block for processingthe multiple input streams can independently process the multiple inputstreams.

The order of each internal block diagram of the mode adaptation modulecan be changed.

Referring to FIG. 3, the mode adaptation block for respectivelyprocessing the multiple input streams can include an input streamsplitter 3000, an input stream synchronizer 3010, a compensating delayblock 3020, a null packet deletion block 3030, a head compression block3040, a CRC encoder 3050, a BB frame slicer 3060 and a BB headerinsertion block 3070. Description will be given of each block of themode adaptation block.

Operations of the CRC encoder 3050, BB frame slicer 3060 and BB headerinsertion block 3070 correspond to those of the CRC encoder, BB frameslicer and BB header insertion block described with reference to FIG. 2and thus description thereof is omitted.

The input stream splitter 3000 can split the input TS, IP, GS streamsinto multiple service or service component (audio, video, etc.) streams.

The input stream synchronizer 3010 may be referred as ISSY. The ISSY canprovide suitable means to guarantee Constant Bit Rate (CBR) and constantend-to-end transmission delay for any input data format. The ISSY isalways used for the case of multiple DPs carrying TS, and optionallyused for multiple DPs carrying GS streams.

The compensating delay block 3020 can delay the split TS packet streamfollowing the insertion of ISSY information to allow a TS packetrecombining mechanism without requiring additional memory in thereceiver.

The null packet deletion block 3030, is used only for the TS inputstream case. Some TS input streams or split TS streams may have a largenumber of null-packets present in order to accommodate VBR (variablebit-rate) services in a CBR TS stream. In this case, in order to avoidunnecessary transmission overhead, null-packets can be identified andnot transmitted. In the receiver, deleted null-packets can bere-inserted in the exact place where they were originally by referenceto a deleted null-packet (DNP) counter that is inserted in thetransmission, thus guaranteeing constant bit-rate and avoiding the needfor time-stamp (PCR) updating.

The head compression block 3040 can provide packet header compression toincrease transmission efficiency for TS or IP input streams. Because thereceiver can have a priori information on certain parts of the header,this known information can be deleted in the transmitter.

For Transport Stream, the receiver has a-priori information about thesync-byte configuration (0x47) and the packet length (188 Byte). If theinput TS stream carries content that has only one PID, i.e., for onlyone service component (video, audio, etc.) or service sub-component (SVCbase layer, SVC enhancement layer, MVC base view or MVC dependentviews), TS packet header compression can be applied (optionally) to theTransport Stream. IP packet header compression is used optionally if theinput steam is an IP stream.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 4 illustrates an input formatting block according to anotherembodiment of the present invention.

The input formatting block illustrated in FIG. 4 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

FIG. 4 illustrates a stream adaptation block of the input formattingmodule when the input signal corresponds to multiple input streams.

Referring to FIG. 4, the mode adaptation block for respectivelyprocessing the multiple input streams can include a scheduler 4000, an1-Frame delay block 4010, a stuffing insertion block 4020, an in-bandsignaling 4030, a BB Frame scrambler 4040, a PLS generation block 4050and a PLS scrambler 4060. Description will be given of each block of thestream adaptation block.

Operations of the stuffing insertion block 4020, the BB Frame scrambler4040, the PLS generation block 4050 and the PLS scrambler 4060correspond to those of the stuffing insertion block, BB scrambler, PLSgeneration block and the PLS scrambler described with reference to FIG.2 and thus description thereof is omitted.

The scheduler 4000 can determine the overall cell allocation across theentire frame from the amount of FECBLOCKs of each DP. Including theallocation for PLS, EAC and FIC, the scheduler generate the values ofPLS2-DYN data, which is transmitted as in-band signaling or PLS cell inFSS of the frame. Details of FEC BLOCK, EAC and FIC will be describedlater.

The 1-Frame delay block 4010 can delay the input data by onetransmission frame such that scheduling information about the next framecan be transmitted through the current frame for in-band signalinginformation to be inserted into the DPs.

The in-band signaling 4030 can insert un-delayed part of the PLS2 datainto a DP of a frame.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 5 illustrates a BICM block according to an embodiment of thepresent invention.

The BICM block illustrated in FIG. 5 corresponds to an embodiment of theBICM block 1010 described with reference to FIG. 1.

As described above, the apparatus for transmitting broadcast signals forfuture broadcast services according to an embodiment of the presentinvention can provide a terrestrial broadcast service, mobile broadcastservice, UHDTV service, etc.

Since QoS (quality of service) depends on characteristics of a serviceprovided by the apparatus for transmitting broadcast signals for futurebroadcast services according to an embodiment of the present invention,data corresponding to respective services needs to be processed throughdifferent schemes. Accordingly, the a BICM block according to anembodiment of the present invention can independently process DPs inputthereto by independently applying SISO, MISO and MIMO schemes to thedata pipes respectively corresponding to data paths. Consequently, theapparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can controlQoS for each service or service component transmitted through each DP.

(a) shows the BICM block shared by the base profile and the handheldprofile and (b) shows the BICM block of the advanced profile.

The BICM block shared by the base profile and the handheld profile andthe BICM block of the advanced profile can include plural processingblocks for processing each DP.

A description will be given of each processing block of the BICM blockfor the base profile and the handheld profile and the BICM block for theadvanced profile.

A processing block 5000 of the BICM block for the base profile and thehandheld profile can include a Data FEC encoder 5010, a bit interleaver5020, a constellation mapper 5030, an SSD (Signal Space Diversity)encoding block 5040 and a time interleaver 5050.

The Data FEC encoder 5010 can perform the FEC encoding on the input BBFto generate FECBLOCK procedure using outer coding (BCH), and innercoding (LDPC). The outer coding (BCH) is optional coding method. Detailsof operations of the Data FEC encoder 5010 will be described later.

The bit interleaver 5020 can interleave outputs of the Data FEC encoder5010 to achieve optimized performance with combination of the LDPC codesand modulation scheme while providing an efficiently implementablestructure. Details of operations of the bit interleaver 5020 will bedescribed later.

The constellation mapper 5030 can modulate each cell word from the bitinterleaver 5020 in the base and the handheld profiles, or cell wordfrom the Cell-word demultiplexer 5010-1 in the advanced profile usingeither QPSK, QAM-16, non-uniform QAM (NUQ-64, NUQ-256, NUQ-1024) ornon-uniform constellation (NUC-16, NUC-64, NUC-256, NUC-1024) to give apower-normalized constellation point, el. This constellation mapping isapplied only for DPs. Observe that QAM-16 and NUQs are square shaped,while NUCs have arbitrary shape. When each constellation is rotated byany multiple of 90 degrees, the rotated constellation exactly overlapswith its original one. This “rotation-sense” symmetric property makesthe capacities and the average powers of the real and imaginarycomponents equal to each other. Both NUQs and NUCs are definedspecifically for each code rate and the particular one used is signaledby the parameter DP_MOD filed in PLS2 data.

The SSD encoding block 5040 can precode cells in two (2D), three (3D),and four (4D) dimensions to increase the reception robustness underdifficult fading conditions.

The time interleaver 5050 can operates at the DP level. The parametersof time interleaving (TI) may be set differently for each DP. Details ofoperations of the time interleaver 5050 will be described later.

A processing block 5000-1 of the BICM block for the advanced profile caninclude the Data FEC encoder, bit interleaver, constellation mapper, andtime interleaver. However, the processing block 5000-1 is distinguishedfrom the processing block 5000 further includes a cell-worddemultiplexer 5010-1 and a MIMO encoding block 5020-1.

Also, the operations of the Data FEC encoder, bit interleaver,constellation mapper, and time interleaver in the processing block5000-1 correspond to those of the Data FEC encoder 5010, bit interleaver5020, constellation mapper 5030, and time interleaver 5050 described andthus description thereof is omitted.

The cell-word demultiplexer 5010-1 is used for the DP of the advancedprofile to divide the single cell-word stream into dual cell-wordstreams for MIMO processing. Details of operations of the cell-worddemultiplexer 5010-1 will be described later.

The MIMO encoding block 5020-1 can processing the output of thecell-word demultiplexer 5010-1 using MIMO encoding scheme. The MIMOencoding scheme was optimized for broadcast signal transmission. TheMIMO technology is a promising way to get a capacity increase but itdepends on channel characteristics. Especially for broadcasting, thestrong LOS component of the channel or a difference in the receivedsignal power between two antennas caused by different signal propagationcharacteristics makes it difficult to get capacity gain from MIMO. Theproposed MIMO encoding scheme overcomes this problem using arotation-based pre-coding and phase randomization of one of the MIMOoutput signals.

MIMO encoding is intended for a 2×2 MIMO system requiring at least twoantennas at both the transmitter and the receiver. Two MIMO encodingmodes are defined in this proposal; full-rate spatial multiplexing(FR-SM) and full-rate full-diversity spatial multiplexing (FRFD-SM). TheFR-SM encoding provides capacity increase with relatively smallcomplexity increase at the receiver side while the FRFD-SM encodingprovides capacity increase and additional diversity gain with a greatcomplexity increase at the receiver side. The proposed MIMO encodingscheme has no restriction on the antenna polarity configuration.

MIMO processing is required for the advanced profile frame, which meansall DPs in the advanced profile frame are processed by the MIMO encoder.MIMO processing is applied at DP level. Pairs of the ConstellationMapper outputs NUQ (e1,i and e2,i) are fed to the input of the MIMOEncoder. Paired MIMO Encoder output (g1,i and g2,i) is transmitted bythe same carrier k and OFDM symbol 1 of their respective TX antennas.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 6 illustrates a BICM block according to another embodiment of thepresent invention.

The BICM block illustrated in FIG. 6 corresponds to an embodiment of theBICM block 1010 described with reference to FIG. 1.

FIG. 6 illustrates a BICM block for protection of physical layersignaling (PLS), emergency alert channel (EAC) and fast informationchannel (FIC). EAC is a part of a frame that carries EAS informationdata and FIC is a logical channel in a frame that carries the mappinginformation between a service and the corresponding base DP. Details ofthe EAC and FIC will be described later.

Referring to FIG. 6, the BICM block for protection of PLS, EAC and FICcan include a PLS FEC encoder 6000, a bit interleaver 6010, aconstellation mapper 6020 and time interleaver 6030.

Also, the PLS FEC encoder 6000 can include a scrambler, BCHencoding/zero insertion block, LDPC encoding block and LDPC paritypunturing block. Description will be given of each block of the BICMblock.

The PLS FEC encoder 6000 can encode the scrambled PLS 1/2 data, EAC andFIC section.

The scrambler can scramble PLS1 data and PLS2 data before BCH encodingand shortened and punctured LDPC encoding.

The BCH encoding/zero insertion block can perform outer encoding on thescrambled PLS 1/2 data using the shortened BCH code for PLS protectionand insert zero bits after the BCH encoding. For PLS1 data only, theoutput bits of the zero insertion may be permuted before LDPC encoding.

The LDPC encoding block can encode the output of the BCH encoding/zeroinsertion block using LDPC code. To generate a complete coded block,Cldpc, parity bits, Pldpc are encoded systematically from eachzero-inserted PLS information block, Ildpc and appended after it.C _(ldpc) =[I _(ldpc) P _(ldpc) ]=[i ₀ ,i ₁ , . . . ,i _(K) _(ldpc) ⁻¹,p ₀ ,p ₁ , . . . ,p _(N) _(ldpc) _(−K) _(ldpc) ⁻¹]  (1)

The LDPC code parameters for PLS1 and PLS2 are as following table 4.

TABLE 4 Signaling Type Kldpc code Ksig Kbch Nbch_parity (=Nbch) NldpcNldpc_parity rate Qldpc PLS1 342 1020 60 1080 4320 3240 1/4  36 PLS2<1021 >1020 2100 2160 7200 5040 3/10 56

The LDPC parity punturing block can perform puncturing on the PLS1 dataand PLS 2 data.

When shortening is applied to the PLS1 data protection, some LDPC paritybits are punctured after LDPC encoding. Also, for the PLS2 dataprotection, the LDPC parity bits of PLS2 are punctured after LDPCencoding. These punctured bits are not transmitted.

The bit interleaver 6010 can interleave the each shortened and puncturedPLS1 data and PLS2 data.

The constellation mapper 6020 can map the bit interleaved PLS1 data andPLS2 data onto constellations.

The time interleaver 6030 can interleave the mapped PLS1 data and PLS2data.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 7 illustrates a frame building block according to one embodiment ofthe present invention.

The frame building block illustrated in FIG. 7 corresponds to anembodiment of the frame building block 1020 described with reference toFIG. 1.

Referring to FIG. 7, the frame building block can include a delaycompensation block 7000, a cell mapper 7010 and a frequency interleaver7020. Description will be given of each block of the frame buildingblock.

The delay compensation block 7000 can adjust the timing between the datapipes and the corresponding PLS data to ensure that they are co-timed atthe transmitter end. The PLS data is delayed by the same amount as datapipes are by addressing the delays of data pipes caused by the InputFormatting block and BICM block. The delay of the BICM block is mainlydue to the time interleaver 5050. In-band signaling data carriesinformation of the next TI group so that they are carried one frameahead of the DPs to be signaled. The Delay Compensating block delaysin-band signaling data accordingly.

The cell mapper 7010 can map PLS, EAC, FIC, DPs, auxiliary streams anddummy cells into the active carriers of the OFDM symbols in the frame.The basic function of the cell mapper 7010 is to map data cells producedby the TIs for each of the DPs, PLS cells, and EAC/FIC cells, if any,into arrays of active OFDM cells corresponding to each of the OFDMsymbols within a frame. Service signaling data (such as PSI(programspecific information)/SI) can be separately gathered and sent by a datapipe. The Cell Mapper operates according to the dynamic informationproduced by the scheduler and the configuration of the frame structure.Details of the frame will be described later.

The frequency interleaver 7020 can randomly interleave data cellsreceived from the cell mapper 7010 to provide frequency diversity. Also,the frequency interleaver 7020 can operate on very OFDM symbol paircomprised of two sequential OFDM symbols using a differentinterleaving-seed order to get maximum interleaving gain in a singleframe. Details of operations of the frequency interleaver 7020 will bedescribed later.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 8 illustrates an OFMD generation block according to an embodimentof the present invention.

The OFMD generation block illustrated in FIG. 8 corresponds to anembodiment of the OFMD generation block 1030 described with reference toFIG. 1.

The OFDM generation block modulates the OFDM carriers by the cellsproduced by the Frame Building block, inserts the pilots, and producesthe time domain signal for transmission. Also, this block subsequentlyinserts guard intervals, and applies PAPR (Peak-to-Average Power Radio)reduction processing to produce the final RF signal.

Referring to FIG. 8, the frame building block can include a pilot andreserved tone insertion block 8000, a 2D-eSFN encoding block 8010, anIFFT (Inverse Fast Fourier Transform) block 8020, a PAPR reduction block8030, a guard interval insertion block 8040, a preamble insertion block8050, other system insertion block 8060 and a DAC block 8070.Description will be given of each block of the frame building block.

The pilot and reserved tone insertion block 8000 can insert pilots andthe reserved tone.

Various cells within the OFDM symbol are modulated with referenceinformation, known as pilots, which have transmitted values known apriori in the receiver. The information of pilot cells is made up ofscattered pilots, continual pilots, edge pilots, FSS (frame signalingsymbol) pilots and FES (frame edge symbol) pilots. Each pilot istransmitted at a particular boosted power level according to pilot typeand pilot pattern. The value of the pilot information is derived from areference sequence, which is a series of values, one for eachtransmitted carrier on any given symbol. The pilots can be used forframe synchronization, frequency synchronization, time synchronization,channel estimation, and transmission mode identification, and also canbe used to follow the phase noise.

Reference information, taken from the reference sequence, is transmittedin scattered pilot cells in every symbol except the preamble, FSS andFES of the frame. Continual pilots are inserted in every symbol of theframe. The number and location of continual pilots depends on both theFFT size and the scattered pilot pattern. The edge carriers are edgepilots in every symbol except for the preamble symbol. They are insertedin order to allow frequency interpolation up to the edge of thespectrum. FSS pilots are inserted in FSS(s) and FES pilots are insertedin FES. They are inserted in order to allow time interpolation up to theedge of the frame.

The system according to an embodiment of the present invention supportsthe SFN network, where distributed MISO scheme is optionally used tosupport very robust transmission mode. The 2D-eSFN is a distributed MISOscheme that uses multiple TX antennas, each of which is located in thedifferent transmitter site in the SFN network.

The 2D-eSFN encoding block 8010 can process a 2D-eSFN processing todistorts the phase of the signals transmitted from multipletransmitters, in order to create both time and frequency diversity inthe SFN configuration. Hence, burst errors due to low flat fading ordeep-fading for a long time can be mitigated.

The IFFT block 8020 can modulate the output from the 2D-eSFN encodingblock 8010 using OFDM modulation scheme. Any cell in the data symbolswhich has not been designated as a pilot (or as a reserved tone) carriesone of the data cells from the frequency interleaver. The cells aremapped to OFDM carriers.

The PAPR reduction block 8030 can perform a PAPR reduction on inputsignal using various PAPR reduction algorithms in the time domain.

The guard interval insertion block 8040 can insert guard intervals andthe preamble insertion block 8050 can insert preamble in front of thesignal. Details of a structure of the preamble will be described later.The other system insertion block 8060 can multiplex signals of aplurality of broadcast transmission/reception systems in the time domainsuch that data of two or more different broadcast transmission/receptionsystems providing broadcast services can be simultaneously transmittedin the same RF signal bandwidth. In this case, the two or more differentbroadcast transmission/reception systems refer to systems providingdifferent broadcast services. The different broadcast services may referto a terrestrial broadcast service, mobile broadcast service, etc. Datarelated to respective broadcast services can be transmitted throughdifferent frames.

The DAC block 8070 can convert an input digital signal into an analogsignal and output the analog signal. The signal output from the DACblock 7800 can be transmitted through multiple output antennas accordingto the physical layer profiles. A Tx antenna according to an embodimentof the present invention can have vertical or horizontal polarity.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to design.

FIG. 9 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention cancorrespond to the apparatus for transmitting broadcast signals forfuture broadcast services, described with reference to FIG. 1.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention can includea synchronization & demodulation module 9000, a frame parsing module9010, a demapping & decoding module 9020, an output processor 9030 and asignaling decoding module 9040. A description will be given of operationof each module of the apparatus for receiving broadcast signals.

The synchronization & demodulation module 9000 can receive input signalsthrough m Rx antennas, perform signal detection and synchronization withrespect to a system corresponding to the apparatus for receivingbroadcast signals and carry out demodulation corresponding to a reverseprocedure of the procedure performed by the apparatus for transmittingbroadcast signals.

The frame parsing module 9100 can parse input signal frames and extractdata through which a service selected by a user is transmitted. If theapparatus for transmitting broadcast signals performs interleaving, theframe parsing module 9100 can carry out deinterleaving corresponding toa reverse procedure of interleaving. In this case, the positions of asignal and data that need to be extracted can be obtained by decodingdata output from the signaling decoding module 9400 to restorescheduling information generated by the apparatus for transmittingbroadcast signals.

The demapping & decoding module 9200 can convert the input signals intobit domain data and then deinterleave the same as necessary. Thedemapping & decoding module 9200 can perform demapping for mappingapplied for transmission efficiency and correct an error generated on atransmission channel through decoding. In this case, the demapping &decoding module 9200 can obtain transmission parameters necessary fordemapping and decoding by decoding the data output from the signalingdecoding module 9400.

The output processor 9300 can perform reverse procedures of variouscompression/signal processing procedures which are applied by theapparatus for transmitting broadcast signals to improve transmissionefficiency. In this case, the output processor 9300 can acquirenecessary control information from data output from the signalingdecoding module 9400. The output of the output processor 8300corresponds to a signal input to the apparatus for transmittingbroadcast signals and may be MPEG-TSs, IP streams (v4 or v6) and genericstreams.

The signaling decoding module 9400 can obtain PLS information from thesignal demodulated by the synchronization & demodulation module 9000. Asdescribed above, the frame parsing module 9100, demapping & decodingmodule 9200 and output processor 9300 can execute functions thereofusing the data output from the signaling decoding module 9400.

FIG. 10 illustrates a frame structure according to an embodiment of thepresent invention.

FIG. 10 shows an example configuration of the frame types and FRUs in asuper-frame. (a) shows a super frame according to an embodiment of thepresent invention, (b) shows FRU (Frame Repetition Unit) according to anembodiment of the present invention, (c) shows frames of variable PHYprofiles in the FRU and (d) shows a structure of a frame.

A super-frame may be composed of eight FRUs. The FRU is a basicmultiplexing unit for TDM of the frames, and is repeated eight times ina super-frame.

Each frame in the FRU belongs to one of the PHY profiles, (base,handheld, advanced) or FEF. The maximum allowed number of the frames inthe FRU is four and a given PHY profile can appear any number of timesfrom zero times to four times in the FRU (e.g., base, base, handheld,advanced). PHY profile definitions can be extended using reserved valuesof the PHY_PROFILE in the preamble, if required.

The FEF part is inserted at the end of the FRU, if included. When theFEF is included in the FRU, the minimum number of FEFs is 8 in asuper-frame. It is not recommended that FEF parts be adjacent to eachother.

One frame is further divided into a number of OFDM symbols and apreamble. As shown in (d), the frame comprises a preamble, one or moreframe signaling symbols (FSS), normal data symbols and a frame edgesymbol (FES).

The preamble is a special symbol that enables fast Futurecast UTB systemsignal detection and provides a set of basic transmission parameters forefficient transmission and reception of the signal. The detaileddescription of the preamble will be will be described later.

The main purpose of the FSS(s) is to carry the PLS data. For fastsynchronization and channel estimation, and hence fast decoding of PLSdata, the FSS has denser pilot pattern than the normal data symbol. TheFES has exactly the same pilots as the FSS, which enables frequency-onlyinterpolation within the FES and temporal interpolation, withoutextrapolation, for symbols immediately preceding the FES.

FIG. 11 illustrates a signaling hierarchy structure of the frameaccording to an embodiment of the present invention.

FIG. 11 illustrates the signaling hierarchy structure, which is splitinto three main parts: the preamble signaling data 11000, the PLS1 data11010 and the PLS2 data 11020. The purpose of the preamble, which iscarried by the preamble symbol in every frame, is to indicate thetransmission type and basic transmission parameters of that frame. ThePLS1 enables the receiver to access and decode the PLS2 data, whichcontains the parameters to access the DP of interest. The PLS2 iscarried in every frame and split into two main parts: PLS2 -STAT dataand PLS2-DYN data. The static and dynamic portion of PLS2 data isfollowed by padding, if necessary.

FIG. 12 illustrates preamble signaling data according to an embodimentof the present invention.

Preamble signaling data carries 21 bits of information that are neededto enable the receiver to access PLS data and trace DPs within the framestructure. Details of the preamble signaling data are as follows:

PHY_PROFILE: This 3-bit field indicates the PHY profile type of thecurrent frame. The mapping of different PHY profile types is given inbelow table 5.

TABLE 5 Value PHY profile 000 Base profile 001 Handheld profile 010Advanced profiled 011~110 Reserved 111 FEF

FFT_SIZE: This 2 bit field indicates the FFT size of the current framewithin a frame-group, as described in below table 6.

TABLE 6 Value FFT size 00  8K FFT 01 16K FFT 10 32K FFT 11 Reserved

GI_FRACTION: This 3 bit field indicates the guard interval fractionvalue in the current super-frame, as described in below table 7.

TABLE 7 Value GI_FRACTION 000 1/5  001 1/10  010 1/20  011 1/40  1001/80  101 1/160 110~111 Reserved

EAC_FLAG: This 1 bit field indicates whether the EAC is provided in thecurrent frame. If this field is set to ‘1’, emergency alert service(EAS) is provided in the current frame. If this field set to ‘0’, EAS isnot carried in the current frame. This field can be switched dynamicallywithin a super-frame.

PILOT_MODE: This 1-bit field indicates whether the pilot mode is mobilemode or fixed mode for the current frame in the current frame-group. Ifthis field is set to ‘0’, mobile pilot mode is used. If the field is setto ‘1’, the fixed pilot mode is used.

PAPR_FLAG: This 1-bit field indicates whether PAPR reduction is used forthe current frame in the current frame-group. If this field is set tovalue ‘1’, tone reservation is used for PAPR reduction. If this field isset to ‘0’, PAPR reduction is not used.

FRU_CONFIGURE: This 3-bit field indicates the PHY profile typeconfigurations of the frame repetition units (FRU) that are present inthe current super-frame. All profile types conveyed in the currentsuper-frame are identified in this field in all preambles in the currentsuper-frame. The 3-bit field has a different definition for eachprofile, as show in below table 8.

TABLE 8 Current Current Current Current PHY_PRO- PHY_PRO- PHY_PRO-PHY_PRO- FILE = FILE = FILE = FILE = ‘000’ ‘001’ ‘010’ ‘111’ (base)(handheld) (advanced) (FEF) FRU_CON- Only base Only Only Only FEF FIGURE= profile handheld advanced present 000 present profile profile presentpresent FRU_CON- Handheld Base Base Base FIGURE = profile profileprofile profile 1XX present present present present FRU_CON- AdvancedAdvanced Handheld Handheld FIGURE = profile profile profile profile X1Xpresent present present present FRU_CON- FEF FEF FEF Advanced FIGURE =present present present profile XX1 present

RESERVED: This 7-bit field is reserved for future use.

FIG. 13 illustrates PLS1 data according to an embodiment of the presentinvention.

PLS1 data provides basic transmission parameters including parametersrequired to enable the reception and decoding of the PLS2. As abovementioned, the PLS1 data remain unchanged for the entire duration of oneframe-group. The detailed definition of the signaling fields of the PLS1data are as follows:

PREAMBLE_DATA: This 20-bit field is a copy of the preamble signalingdata excluding the EAC_FLAG.

NUM_FRAME_FRU: This 2-bit field indicates the number of the frames perFRU.

PAYLOAD_TYPE: This 3-bit field indicates the format of the payload datacarried in the frame-group. PAYLOAD_TYPE is signaled as shown in table9.

TABLE 9 Value Payload type 1XX TS stream is transmitted X1X IP stream istransmitted XX1 GS stream is transmitted

NUM_FSS: This 2-bit field indicates the number of FSS symbols in thecurrent frame.

SYSTEM_VERSION: This 8-bit field indicates the version of thetransmitted signal format. The SYSTEM_VERSION is divided into two 4-bitfields, which are a major version and a minor version.

Major version: The MSB four bits of SYSTEM_VERSION field indicate majorversion information. A change in the major version field indicates anon-backward-compatible change. The default value is ‘0000’. For theversion described in this standard, the value is set to ‘0000’.

Minor version: The LSB four bits of SYSTEM_VERSION field indicate minorversion information. A change in the minor version field isbackward-compatible.

CELL_ID: This is a 16-bit field which uniquely identifies a geographiccell in an ATSC network. An ATSC cell coverage area may consist of oneor more frequencies, depending on the number of frequencies used perFuturecast UTB system. If the value of the CELL_ID is not known orunspecified, this field is set to ‘0’.

NETWORK_ID: This is a 16-bit field which uniquely identifies the currentATSC network.

SYSTEM_ID: This 16-bit field uniquely identifies the Futurecast UTBsystem within the ATSC network. The Futurecast UTB system is theterrestrial broadcast system whose input is one or more input streams(TS, IP, GS) and whose output is an RF signal. The Futurecast UTB systemcarries one or more PHY profiles and FEF, if any. The same FuturecastUTB system may carry different input streams and use different RFfrequencies in different geographical areas, allowing local serviceinsertion. The frame structure and scheduling is controlled in one placeand is identical for all transmissions within a Futurecast UTB system.One or more Futurecast UTB systems may have the same SYSTEM_ID meaningthat they all have the same physical layer structure and configuration.

The following loop consists of FRU_PHY_PROFILE, FRU_FRAME_LENGTH,FRU_GI_FRACTION, and RESERVED which are used to indicate the FRUconfiguration and the length of each frame type. The loop size is fixedso that four PHY profiles (including a FEF) are signaled within the FRU.If NUM_FRAME_FRU is less than 4, the unused fields are filled withzeros.

FRU_PHY_PROFILE: This 3-bit field indicates the PHY profile type of the(i+1)th (i is the loop index) frame of the associated FRU. This fielduses the same signaling format as shown in the table 8.

FRU_FRAME_LENGTH: This 2-bit field indicates the length of the (i+1)thframe of the associated FRU. Using FRU_FRAME_LENGTH together withFRU_GI_FRACTION, the exact value of the frame duration can be obtained.

FRU_GI_FRACTION: This 3-bit field indicates the guard interval fractionvalue of the (i+1)th frame of the associated FRU. FRU_GI_FRACTION issignaled according to the table 7.

RESERVED: This 4-bit field is reserved for future use.

The following fields provide parameters for decoding the PLS2 data.

PLS2_FEC_TYPE: This 2-bit field indicates the FEC type used by the PLS2protection. The FEC type is signaled according to table 10. The detailsof the LDPC codes will be described later.

TABLE 10 Contents PLS2 FEC type 00 4K-1/4 and 7K-3/10 LDPC codes 01~11Reserved

PLS2_MOD: This 3-bit field indicates the modulation type used by thePLS2. The modulation type is signaled according to table 11.

TABLE 11 Value PLS2_MODE 000 BPSK 001 QPSK 010 QAM-16 011 NUQ-64 100~111Reserved

PLS2_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block, thesize (specified as the number of QAM cells) of the collection of fullcoded blocks for PLS2 that is carried in the current frame-group. Thisvalue is constant during the entire duration of the current frame-group.

PLS2_STAT_SIZE_BIT: This 14-bit field indicates the size, in bits, ofthe PLS2-STAT for the current frame-group. This value is constant duringthe entire duration of the current frame-group.

PLS2_DYN_SIZE_BIT: This 14-bit field indicates the size, in bits, of thePLS2-DYN for the current frame-group. This value is constant during theentire duration of the current frame-group.

PLS2_REP_FLAG: This 1-bit flag indicates whether the PLS2 repetitionmode is used in the current frame-group. When this field is set to value‘1’, the PLS2 repetition mode is activated. When this field is set tovalue ‘0’, the PLS2 repetition mode is deactivated.

PLS2_REP_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block,the size (specified as the number of QAM cells) of the collection ofpartial coded blocks for PLS2 carried in every frame of the currentframe-group, when PLS2 repetition is used. If repetition is not used,the value of this field is equal to 0. This value is constant during theentire duration of the current frame-group.

PLS2_NEXT_FEC_TYPE: This 2-bit field indicates the FEC type used forPLS2 that is carried in every frame of the next frame-group. The FECtype is signaled according to the table 10.

PLS2_NEXT_MOD: This 3-bit field indicates the modulation type used forPLS2 that is carried in every frame of the next frame-group. Themodulation type is signaled according to the table 11.

PLS2_NEXT_REP_FLAG: This 1-bit flag indicates whether the PLS2repetition mode is used in the next frame-group. When this field is setto value ‘1’, the PLS2 repetition mode is activated. When this field isset to value ‘0’, the PLS2 repetition mode is deactivated.

PLS2_NEXT_REP_SIZE_CELL: This 15-bit field indicates Ctotal_full_block,The size (specified as the number of QAM cells) of the collection offull coded blocks for PLS2 that is carried in every frame of the nextframe-group, when PLS2 repetition is used. If repetition is not used inthe next frame-group, the value of this field is equal to 0. This valueis constant during the entire duration of the current frame-group.

PLS2_NEXT_REP_STAT_SIZE_BIT: This 14-bit field indicates the size, inbits, of the PLS2-STAT for the next frame-group. This value is constantin the current frame-group.

PLS2_NEXT_REP_DYN_SIZE_BIT: This 14-bit field indicates the size, inbits, of the PLS2-DYN for the next frame-group. This value is constantin the current frame-group.

PLS2_AP_MODE: This 2-bit field indicates whether additional parity isprovided for PLS2 in the current frame-group. This value is constantduring the entire duration of the current frame-group. The below table12 gives the values of this field. When this field is set to ‘00’,additional parity is not used for the PLS2 in the current frame-group.

TABLE 12 Value PLS2-AP mode 00 AP is not provided 01 AP1 mode 10~11Reserved

PLS2_AP_SIZE_CELL: This 15-bit field indicates the size (specified asthe number of QAM cells) of the additional parity bits of the PLS2. Thisvalue is constant during the entire duration of the current frame-group.

PLS2_NEXT_AP_MODE: This 2-bit field indicates whether additional parityis provided for PLS2 signaling in every frame of next frame-group. Thisvalue is constant during the entire duration of the current frame-group.The table 12 defines the values of this field

PLS2_NEXT_AP_SIZE_CELL: This 15-bit field indicates the size (specifiedas the number of QAM cells) of the additional parity bits of the PLS2 inevery frame of the next frame-group. This value is constant during theentire duration of the current frame-group.

RESERVED: This 32-bit field is reserved for future use.

CRC_(—)32: A 32-bit error detection code, which is applied to the entirePLS1 signaling.

FIG. 14 illustrates PLS2 data according to an embodiment of the presentinvention.

FIG. 14 illustrates PLS2-STAT data of the PLS2 data. The PLS2-STAT dataare the same within a frame-group, while the PLS2-DYN data provideinformation that is specific for the current frame.

The details of fields of the PLS2-STAT data are as follows:

FIC_FLAG: This 1-bit field indicates whether the FIC is used in thecurrent frame-group. If this field is set to ‘1’, the FIC is provided inthe current frame. If this field set to ‘0’, the FIC is not carried inthe current frame. This value is constant during the entire duration ofthe current frame-group.

AUX_FLAG: This 1-bit field indicates whether the auxiliary stream(s) isused in the current frame-group. If this field is set to ‘1’, theauxiliary stream is provided in the current frame. If this field set to‘0’, the auxiliary stream is not carried in the current frame. Thisvalue is constant during the entire duration of current frame-group.

NUM_DP: This 6-bit field indicates the number of DPs carried within thecurrent frame. The value of this field ranges from 1 to 64, and thenumber of DPs is NUM_DP+1.

DP_ID: This 6-bit field identifies uniquely a DP within a PHY profile.

DP_TYPE: This 3-bit field indicates the type of the DP. This is signaledaccording to the below table 13.

TABLE 13 Value DP Type 000 DP Type 1 001 DP Type 2 010~111 reserved

DP_GROUP_ID: This 8-bit field identifies the DP group with which thecurrent DP is associated. This can be used by a receiver to access theDPs of the service components associated with a particular service,which will have the same DP_GROUP_ID.

BASE DP_ID: This 6-bit field indicates the DP carrying service signalingdata (such as PSI/SI) used in the Management layer. The DP indicated byBASE_DP_ID may be either a normal DP carrying the service signaling dataalong with the service data or a dedicated DP carrying only the servicesignaling data

DP_FEC_TYPE: This 2-bit field indicates the FEC type used by theassociated DP. The FEC type is signaled according to the below table 14.

TABLE 14 Value FEC_TYPE 00 16K LDPC 01 64K LDPC 10~11 Reserved

DP_COD: This 4-bit field indicates the code rate used by the associatedDP. The code rate is signaled according to the below table 15.

TABLE 15 Value Code rate 0000  5/15 0001  6/15 0010  7/15 0011  8/150100  9/15 0101 10/15 0110 11/15 0111 12/15 1000 13/15 1001~1111Reserved

DP_MOD: This 4-bit field indicates the modulation used by the associatedDP. The modulation is signaled according to the below table 16.

TABLE 16 Value Modulation 0000 QPSK 0001 QAM-16 0010 NUQ-64 0011 NUQ-2560100 NUQ-1024 0101 NUC-16 0110 NUC-64 0111 NUC-256 1000 NUC-10241001~1111 reserved

DP_SSD_FLAG: This 1-bit field indicates whether the SSD mode is used inthe associated DP. If this field is set to value ‘1’, SSD is used. Ifthis field is set to value ‘0’, SSD is not used.

The following field appears only if PHY_PROFILE is equal to ‘010’, whichindicates the advanced profile:

DP_MIMO: This 3-bit field indicates which type of MIMO encoding processis applied to the associated DP. The type of MIMO encoding process issignaled according to the table 17.

TABLE 17 Value MIMO encoding 000 FR-SM 001 FRFD-SM 010~111 reserved

DP_TI_TYPE: This 1-bit field indicates the type of time-interleaving. Avalue of ‘0’ indicates that one TI group corresponds to one frame andcontains one or more TI-blocks. A value of ‘1’ indicates that one TIgroup is carried in more than one frame and contains only one TI-block.

DP_TI_LENGTH: The use of this 2-bit field (the allowed values are only1, 2, 4, 8) is determined by the values set within the DP_TI_TYPE fieldas follows:

If the DP_TI_TYPE is set to the value ‘1’, this field indicates PI, thenumber of the frames to which each TI group is mapped, and there is oneTI-block per TI group (NTI=1). The allowed PI values with 2-bit fieldare defined in the below table 18.

If the DP_TI_TYPE is set to the value ‘0’, this field indicates thenumber of TI-blocks NTI per TI group, and there is one TI group perframe (PI=1). The allowed PI values with 2-bit field are defined in thebelow table 18.

TABLE 18 2-bit field PI NTI 00 1 1 01 2 2 10 4 3 11 8 4

DP_FRAME_INTERVAL: This 2-bit field indicates the frame interval (IJUMP)within the frame-group for the associated DP and the allowed values are1, 2, 4, 8 (the corresponding 2-bit field is ‘00’, ‘01’, ‘10’, or ‘11’,respectively). For DPs that do not appear every frame of theframe-group, the value of this field is equal to the interval betweensuccessive frames. For example, if a DP appears on the frames 1, 5, 9,13, etc., this field is set to ‘4’. For DPs that appear in every frame,this field is set to ‘1’.

DP_TI_BYPASS: This 1-bit field determines the availability of timeinterleaver 5050. If time interleaving is not used for a DP, it is setto ‘1’. Whereas if time interleaving is used it is set to ‘0’.

DP_FIRST_FRAME_IDX: This 5-bit field indicates the index of the firstframe of the super-frame in which the current DP occurs. The value ofDP_FIRST_FRAME_IDX ranges from 0 to 31

DP_NUM_BLOCK_MAX: This 10-bit field indicates the maximum value ofDP_NUM_BLOCKS for this DP. The value of this field has the same range asDP_NUM_BLOCKS.

DP_PAYLOAD_TYPE: This 2-bit field indicates the type of the payload datacarried by the given DP. DP_PAYLOAD_TYPE is signaled according to thebelow table 19.

TABLE 19 Value Payload Type 00 TS. 01 IP 10 GS 11 reserved

DP_INBAND_MODE: This 2-bit field indicates whether the current DPcarries in-band signaling information. The in-band signaling type issignaled according to the below table 20.

TABLE 20 Value In-band mode 00 In-band signaling is not carried. 01INBAND-PLS is carried only 10 INBAND-ISSY is carried only 11 INBAND-PLSand INBAND-ISSY are carried

DP_PROTOCOL_TYPE: This 2-bit field indicates the protocol type of thepayload carried by the given DP. It is signaled according to the belowtable 21 when input payload types are selected.

TABLE 21 If If If DP_PAYLOAD_ DP_PAYLOAD_ DP_PAYLOAD_ TYPE TYPE TYPEValue Is TS Is IP Is GS 00 MPEG2-TS IPv4 (Note) 01 Reserved IPv6Reserved 10 Reserved Reserved Reserved 11 Reserved Reserved Reserved

DP_CRC_MODE: This 2-bit field indicates whether CRC encoding is used inthe Input Formatting block. The CRC mode is signaled according to thebelow table 22.

TABLE 22 Value CRC mode 00 Not used 01 CRC-8 10 CRC-16 11 CRC-32

DNP_MODE: This 2-bit field indicates the null-packet deletion mode usedby the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). DNP_MODEis signaled according to the below table 23. If DP_PAYLOAD_TYPE is notTS (‘00’), DNP_MODE is set to the value ‘00’.

TABLE 23 Value Null-packet deletion mode 00 Not used 01 DNP-NORMAL 10DNP-OFFSET 11 reserved

ISSY_MODE: This 2-bit field indicates the ISSY mode used by theassociated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). The ISSY_MODE issignaled according to the below table 24 If DP_PAYLOAD_TYPE is not TS(‘00’), ISSY_MODE is set to the value ‘00’.

TABLE 24 Value ISSY mode 00 Not used 01 ISSY-UP 10 ISSY-BBF 11 reserved

HC_MODE_TS: This 2-bit field indicates the TS header compression modeused by the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). TheHC_MODE_TS is signaled according to the below table 25.

TABLE 25 Value Header compression mode 00 HC_MODE_TS 1 01 HC_MODE_TS 210 HC_MODE_TS 3 11 HC_MODE_TS 4

HC_MODE_IP: This 2-bit field indicates the IP header compression modewhen DP_PAYLOAD_TYPE is set to IP (‘01’). The HC_MODE_IP is signaledaccording to the below table 26.

TABLE 26 Value Header compression mode 00 No compression 01 HC_MODE_IP 110~11 reserved

PID: This 13-bit field indicates the PID number for TS headercompression when DP_PAYLOAD_TYPE is set to TS (‘00’) and HC_MODE_TS isset to ‘01’ or ‘10’.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if FIC_FLAG is equal to ‘1’:

FIC_VERSION: This 8-bit field indicates the version number of the FIC.

FIC_LENGTH_BYTE: This 13-bit field indicates the length, in bytes, ofthe FIC.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if AUX_FLAG is equal to ‘1’:

NUM_AUX: This 4-bit field indicates the number of auxiliary streams.Zero means no auxiliary streams are used.

AUX_CONFIG_RFU: This 8-bit field is reserved for future use.

AUX_STREAM_TYPE: This 4-bit is reserved for future use for indicatingthe type of the current auxiliary stream.

AUX_PRIVATE_CONFIG: This 28-bit field is reserved for future use forsignaling auxiliary streams.

FIG. 15 illustrates PLS2 data according to another embodiment of thepresent invention.

FIG. 15 illustrates PLS2-DYN data of the PLS2 data. The values of thePLS2-DYN data may change during the duration of one frame-group, whilethe size of fields remains constant.

The details of fields of the PLS2-DYN data are as follows:

FRAME_INDEX: This 5-bit field indicates the frame index of the currentframe within the super-frame. The index of the first frame of thesuper-frame is set to ‘0’.

PLS_CHANGE_COUNTER: This 4-bit field indicates the number ofsuper-frames ahead where the configuration will change. The nextsuper-frame with changes in the configuration is indicated by the valuesignaled within this field. If this field is set to the value ‘0000’, itmeans that no scheduled change is foreseen: e.g., value ‘1’ indicatesthat there is a change in the next super-frame.

FIC_CHANGE_COUNTER: This 4-bit field indicates the number ofsuper-frames ahead where the configuration (i.e., the contents of theFIC) will change. The next super-frame with changes in the configurationis indicated by the value signaled within this field. If this field isset to the value ‘0000’, it means that no scheduled change is foreseen:e.g. value ‘0001’ indicates that there is a change in the nextsuper-frame.

RESERVED: This 16-bit field is reserved for future use.

The following fields appear in the loop over NUM_DP, which describe theparameters associated with the DP carried in the current frame.

DP_ID: This 6-bit field indicates uniquely the DP within a PHY profile.

DP_START: This 15-bit (or 13-bit) field indicates the start position ofthe first of the DPs using the DPU addressing scheme. The DP_START fieldhas differing length according to the PHY profile and FFT size as shownin the below table 27.

TABLE 27 DP_START field size PHY profile 64K 16K Base 13 bits 15 bitsHandheld — 13 bits Advanced 13 bits 15 bits

DP_NUM_BLOCK: This 10-bit field indicates the number of FEC blocks inthe current TI group for the current DP. The value of DP_NUM_BLOCKranges from 0 to 1023

RESERVED: This 8-bit field is reserved for future use.

The following fields indicate the FIC parameters associated with theEAC.

EAC_FLAG: This 1-bit field indicates the existence of the EAC in thecurrent frame. This bit is the same value as the EAC_FLAG in thepreamble.

EAS_WAKE_UP_VERSION_NUM: This 8-bit field indicates the version numberof a wake-up indication.

If the EAC_FLAG field is equal to ‘1’, the following 12 bits areallocated for EAC_LENGTH_BYTE field. If the EAC_FLAG field is equal to‘0’, the following 12 bits are allocated for EAC_COUNTER.

EAC_LENGTH_BYTE: This 12-bit field indicates the length, in byte, of theEAC.

EAC_COUNTER: This 12-bit field indicates the number of the frames beforethe frame where the EAC arrives.

The following field appears only if the AUX_FLAG field is equal to ‘1’:

AUX_PRIVATE_DYN: This 48-bit field is reserved for future use forsignaling auxiliary streams. The meaning of this field depends on thevalue of AUX_STREAM_TYPE in the configurable PLS2-STAT.

CRC_(—)32: A 32-bit error detection code, which is applied to the entirePLS2.

FIG. 16 illustrates a logical structure of a frame according to anembodiment of the present invention.

As above mentioned, the PLS, EAC, FIC, DPs, auxiliary streams and dummycells are mapped into the active carriers of the OFDM symbols in theframe. The PLS1 and PLS2 are first mapped into one or more FSS(s). Afterthat, EAC cells, if any, are mapped immediately following the PLS field,followed next by FIC cells, if any. The DPs are mapped next after thePLS or EAC, FIC, if any. Type 1 DPs follows first, and Type 2 DPs next.The details of a type of the DP will be described later. In some case,DPs may carry some special data for EAS or service signaling data. Theauxiliary stream or streams, if any, follow the DPs, which in turn arefollowed by dummy cells. Mapping them all together in the abovementioned order, i.e. PLS, EAC, FIC, DPs, auxiliary streams and dummydata cells exactly fill the cell capacity in the frame.

FIG. 17 illustrates PLS mapping according to an embodiment of thepresent invention.

PLS cells are mapped to the active carriers of FSS(s). Depending on thenumber of cells occupied by PLS, one or more symbols are designated asFSS(s), and the number of FSS(s) NFSS is signaled by NUM_FSS in PLS1.The FSS is a special symbol for carrying PLS cells. Since robustness andlatency are critical issues in the PLS, the FSS(s) has higher density ofpilots allowing fast synchronization and frequency-only interpolationwithin the FSS.

PLS cells are mapped to active carriers of the NFSS FSS(s) in a top-downmanner as shown in an example in FIG. 17. The PLS1 cells are mappedfirst from the first cell of the first FSS in an increasing order of thecell index. The PLS2 cells follow immediately after the last cell of thePLS1 and mapping continues downward until the last cell index of thefirst FSS. If the total number of required PLS cells exceeds the numberof active carriers of one FSS, mapping proceeds to the next FSS andcontinues in exactly the same manner as the first FSS.

After PLS mapping is completed, DPs are carried next. If EAC, FIC orboth are present in the current frame, they are placed between PLS and“normal” DPs.

FIG. 18 illustrates EAC mapping according to an embodiment of thepresent invention.

EAC is a dedicated channel for carrying EAS messages and links to theDPs for EAS. EAS support is provided but EAC itself may or may not bepresent in every frame. EAC, if any, is mapped immediately after thePLS2 cells. EAC is not preceded by any of the FIC, DPs, auxiliarystreams or dummy cells other than the PLS cells. The procedure ofmapping the EAC cells is exactly the same as that of the PLS.

The EAC cells are mapped from the next cell of the PLS2 in increasingorder of the cell index as shown in the example in FIG. 18. Depending onthe EAS message size, EAC cells may occupy a few symbols, as shown inFIG. 18.

EAC cells follow immediately after the last cell of the PLS2, andmapping continues downward until the last cell index of the last FSS. Ifthe total number of required EAC cells exceeds the number of remainingactive carriers of the last FSS mapping proceeds to the next symbol andcontinues in exactly the same manner as FSS(s). The next symbol formapping in this case is the normal data symbol, which has more activecarriers than a FSS.

After EAC mapping is completed, the FIC is carried next, if any exists.If FIC is not transmitted (as signaled in the PLS2 field), DPs followimmediately after the last cell of the EAC.

FIG. 19 illustrates FIC mapping according to an embodiment of thepresent invention.

(a) shows an example mapping of an FIC cell without EAC and (b) shows anexample mapping of an FIC cell with EAC.

FIC is a dedicated channel for carrying cross-layer information toenable fast service acquisition and channel scanning. This informationprimarily includes channel binding information between DPs and theservices of each broadcaster. For fast scan, a receiver can decode FICand obtain information such as broadcaster ID, number of services, andBASE_DP_ID. For fast service acquisition, in addition to FIC, base DPcan be decoded using BASE_DP_ID. Other than the content it carries, abase DP is encoded and mapped to a frame in exactly the same way as anormal DP. Therefore, no additional description is required for a baseDP. The FIC data is generated and consumed in the Management Layer. Thecontent of FIC data is as described in the Management Layerspecification.

The FIC data is optional and the use of FIC is signaled by the FIC_FLAGparameter in the static part of the PLS2. If FIC is used, FIC_FLAG isset to ‘1’ and the signaling field for FIC is defined in the static partof PLS2. Signaled in this field are FIC_VERSION, and FIC_LENGTH_BYTE.FIC uses the same modulation, coding and time interleaving parameters asPLS2. FIC shares the same signaling parameters such as PLS2_MOD andPLS2_FEC. FIC data, if any, is mapped immediately after PLS2 or EAC ifany. FIC is not preceded by any normal DPs, auxiliary streams or dummycells. The method of mapping FIC cells is exactly the same as that ofEAC which is again the same as PLS.

Without EAC after PLS, FIC cells are mapped from the next cell of thePLS2 in an increasing order of the cell index as shown in an example in(a). Depending on the FIC data size, FIC cells may be mapped over a fewsymbols, as shown in (b).

FIC cells follow immediately after the last cell of the PLS2, andmapping continues downward until the last cell index of the last FSS. Ifthe total number of required FIC cells exceeds the number of remainingactive carriers of the last FSS, mapping proceeds to the next symbol andcontinues in exactly the same manner as FSS(s). The next symbol formapping in this case is the normal data symbol which has more activecarriers than a FSS.

If EAS messages are transmitted in the current frame, EAC precedes FIC,and FIC cells are mapped from the next cell of the EAC in an increasingorder of the cell index as shown in (b).

After FIC mapping is completed, one or more DPs are mapped, followed byauxiliary streams, if any, and dummy cells.

FIG. 20 illustrates a type of DP according to an embodiment of thepresent invention.

shows type 1 DP and (b) shows type 2 DP.

After the preceding channels, i.e., PLS, EAC and FIC, are mapped, cellsof the DPs are mapped. A DP is categorized into one of two typesaccording to mapping method:

Type 1 DP: DP is mapped by TDM

Type 2 DP: DP is mapped by FDM

The type of DP is indicated by DP_TYPE field in the static part of PLS2.FIG. 20 illustrates the mapping orders of Type 1 DPs and Type 2 DPs.Type 1 DPs are first mapped in the increasing order of cell index, andthen after reaching the last cell index, the symbol index is increasedby one. Within the next symbol, the DP continues to be mapped in theincreasing order of cell index starting from p=0. With a number of DPsmapped together in one frame, each of the Type 1 DPs are grouped intime, similar to TDM multiplexing of DPs.

Type 2 DPs are first mapped in the increasing order of symbol index, andthen after reaching the last OFDM symbol of the frame, the cell indexincreases by one and the symbol index rolls back to the first availablesymbol and then increases from that symbol index. After mapping a numberof DPs together in one frame, each of the Type 2 DPs are grouped infrequency together, similar to FDM multiplexing of DPs.

Type 1 DPs and Type 2 DPs can coexist in a frame if needed with onerestriction; Type 1 DPs always precede Type 2 DPs. The total number ofOFDM cells carrying Type 1 and Type 2 DPs cannot exceed the total numberof OFDM cells available for transmission of DPs:D _(DP1) +D _(DP2) ≦D _(DP)  (2)

where DDP1 is the number of OFDM cells occupied by Type 1 DPs, DDP2 isthe number of cells occupied by Type 2 DPs. Since PLS, EAC, FIC are allmapped in the same way as Type 1 DP, they all follow “Type 1 mappingrule”. Hence, overall, Type 1 mapping always precedes Type 2 mapping.

FIG. 21 illustrates DP mapping according to an embodiment of the presentinvention.

shows an addressing of OFDM cells for mapping type 1 DPs and (b) showsthe addressing of OFDM cells for mapping for type 2 DPs.

Addressing of OFDM cells for mapping Type 1 DPs (0, . . . , DDP1-1) isdefined for the active data cells of Type 1 DPs. The addressing schemedefines the order in which the cells from the TIs for each of the Type 1DPs are allocated to the active data cells. It is also used to signalthe locations of the DPs in the dynamic part of the PLS2.

Without EAC and FIC, address 0 refers to the cell immediately followingthe last cell carrying PLS in the last FSS. If EAC is transmitted andFIC is not in the corresponding frame, address 0 refers to the cellimmediately following the last cell carrying EAC. If FIC is transmittedin the corresponding frame, address 0 refers to the cell immediatelyfollowing the last cell carrying FIC. Address 0 for Type 1 DPs can becalculated considering two different cases as shown in (a). In theexample in (a), PLS, EAC and FIC are assumed to be all transmitted.Extension to the cases where either or both of EAC and FIC are omittedis straightforward. If there are remaining cells in the FSS aftermapping all the cells up to FIC as shown on the left side of (a).

Addressing of OFDM cells for mapping Type 2 DPs (0, . . . , DDP2-1) isdefined for the active data cells of Type 2 DPs. The addressing schemedefines the order in which the cells from the TIs for each of the Type 2DPs are allocated to the active data cells. It is also used to signalthe locations of the DPs in the dynamic part of the PLS2.

Three slightly different cases are possible as shown in (b). For thefirst case shown on the left side of (b), cells in the last FSS areavailable for Type 2 DP mapping. For the second case shown in themiddle, FIC occupies cells of a normal symbol, but the number of FICcells on that symbol is not larger than CFSS. The third case, shown onthe right side in (b), is the same as the second case except that thenumber of FIC cells mapped on that symbol exceeds CFSS.

The extension to the case where Type 1 DP(s) precede Type 2 DP(s) isstraightforward since PLS, EAC and FIC follow the same “Type 1 mappingrule” as the Type 1 DP(s).

A data pipe unit (DPU) is a basic unit for allocating data cells to a DPin a frame.

A DPU is defined as a signaling unit for locating DPs in a frame. A CellMapper 7010 may map the cells produced by the TIs for each of the DPs. ATime interleaver 5050 outputs a series of TI-blocks and each TI-blockcomprises a variable number of XFECBLOCKs which is in turn composed of aset of cells. The number of cells in an XFECBLOCK, Ncells, is dependenton the FECBLOCK size, Nldpc, and the number of transmitted bits perconstellation symbol. A DPU is defined as the greatest common divisor ofall possible values of the number of cells in a XFECBLOCK, Ncells,supported in a given PHY profile. The length of a DPU in cells isdefined as LDPU. Since each PHY profile supports different combinationsof FECBLOCK size and a different number of bits per constellationsymbol, LDPU is defined on a PHY profile basis.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention before bit interleaving. As above mentioned, Data FECencoder may perform the FEC encoding on the input BBF to generateFECBLOCK procedure using outer coding (BCH), and inner coding (LDPC).The illustrated FEC structure corresponds to the FECBLOCK. Also, theFECBLOCK and the FEC structure have same value corresponding to a lengthof LDPC codeword.

The BCH encoding is applied to each BBF (Kbch bits), and then LDPCencoding is applied to BCH-encoded BBF (Kldpc bits=Nbch bits) asillustrated in FIG. 22.

The value of Nldpc is either 64800 bits (long FECBLOCK) or 16200 bits(short FECBLOCK).

The below table 28 and table 29 show FEC encoding parameters for a longFECBLOCK and a short FECBLOCK, respectively.

TABLE 28 BCH error LDPC correction Nbch- Rate Nldpc Kldpc Kbchcapability Kbch  5/15 64800 21600 21408 12 192  6/15 25920 25728  7/1530240 30048  8/15 34560 34368  9/15 38880 38688 10/15 43200 43008 11/1547520 47328 12/15 51840 51648 13/15 56160 55968

TABLE 29 BCH error LDPC correction Nbch- Rate Nldpc Kldpc Kbchcapability Kbch  5/15 16200 5400 5232 12 168  6/15 6480 6312  7/15 75607392  8/15 8640 8472  9/15 9720 9552 10/15 10800 10632 11/15 11880 1171212/15 12960 12792 13/15 14040 13872

The details of operations of the BCH encoding and LDPC encoding are asfollows:

A 12-error correcting BCH code is used for outer encoding of the BBF.The BCH generator polynomial for short FECBLOCK and long FECBLOCK areobtained by multiplying together all polynomials.

LDPC code is used to encode the output of the outer BCH encoding. Togenerate a completed Bldpc (FECBLOCK), Pldpc (parity bits) is encodedsystematically from each Ildpc (BCH-encoded BBF), and appended to Ildpc.The completed Bldpc (FECBLOCK) are expressed as follow Math figure.B _(ldpc) =[I _(ldpc) P _(ldpc) ]=[i ₀ ,i ₁ , . . . ,i _(K) _(ldpc) ⁻¹,p ₀ ,p ₁ , . . . ,p _(N) _(ldpc) _(−K) _(ldpc) ⁻¹]  (3)

The parameters for long FECBLOCK and short FECBLOCK are given in theabove table 28 and 29, respectively.

The detailed procedure to calculate Nldpc−Kldpc parity bits for longFECBLOCK, is as follows:

1) Initialize the parity bits,p ₀ =p ₁ =p ₂ = . . . =p _(N) _(ldpc) _(−K) _(ldpc) ⁻¹=0  (4)

2) Accumulate the first information bit-i0, at parity bit addressesspecified in the first row of addresses of parity check matrix. Thedetails of addresses of parity check matrix will be described later. Forexample, for rate 13/15:p ₉₈₃ =p ₉₈₃ ⊕i ₀ p ₂₈₁₅ −p ₂₈₁₅ ⊕i ₀p ₄₈₃₇ =p ₄₈₃₇ ⊕i ₀ p ₄₉₈₉ =p ₄₉₈₉ ⊕i ₀p ₆₁₃₈ =p ₆₁₃₈ ⊕i ₀ p ₆₄₅₈ =p ₆₄₅₈ ⊕i ₀p ₆₉₂₁ =p ₆₉₂₁ ⊕i ₀ p ₆₉₇₄ =p ₆₉₇₄ ⊕i ₀p ₇₅₇₂ =p ₇₅₇₂ ⊕i ₀ p ₈₂₆₀ =p ₈₂₆₀ ⊕i ₀p ₈₄₉₆ =p ₈₄₉₆ ⊕i ₀  (5)

3) For the next 359 information bits, is, s=1, 2, . . . , 359 accumulateis at parity bit addresses using following Math figure.{x+(s mod 360)×Q _(ldpc)} mod(N _(ldpc) −K _(ldpc))  (6)

where x denotes the address of the parity bit accumulator correspondingto the first bit i0, and Qldpc is a code rate dependent constantspecified in the addresses of parity check matrix. Continuing with theexample, Qldpc=24 for rate 13/15, so for information bit i1, thefollowing operations are performed:p ₁₀₀₇ =p ₁₀₀₇ ⊕i ₁ p ₂₈₃₉ =p ₂₈₃₉ ⊕i ₁p ₄₈₆₁ =p ₄₈₆₁ ⊕i ₁ p ₅₀₁₃ =p ₅₀₁₃ ⊕i ₁p ₆₁₆₂ =p ₆₁₆₂ ⊕i ₁ p ₆₄₈₂ =p ₆₄₈₂ ⊕i ₁p ₆₉₄₅ =p ₆₉₄₅ ⊕i ₁ p ₆₉₉₈ =p ₆₉₉₈ ⊕i ₁p ₇₅₉₆ =p ₇₅₉₆ ⊕i ₁ p ₈₂₈₄ =p ₈₂₈₄ ⊕i ₁p ₈₅₂₀ =p ₈₅₂₀ ⊕i ₁  (7)

4) For the 361st information bit i360, the addresses of the parity bitaccumulators are given in the second row of the addresses of paritycheck matrix. In a similar manner the addresses of the parity bitaccumulators for the following 359 information bits is, s=361, 362, . .. , 719 are obtained using the Math FIG. 6, where x denotes the addressof the parity bit accumulator corresponding to the information bit i360,i.e., the entries in the second row of the addresses of parity checkmatrix.

5) In a similar manner, for every group of 360 new information bits, anew row from addresses of parity check matrixes used to find theaddresses of the parity bit accumulators.

After all of the information bits are exhausted, the final parity bitsare obtained as follows:

6) Sequentially perform the following operations starting with i=1p _(i) =p _(i) ⊕p _(i−1) , i=1,2, . . . ,N _(ldpc) −K _(ldpc)−1  (8)

where final content of pi, i=0,1, . . . Nldpc−Kldpc−1 is equal to theparity bit pi.

TABLE 30 Code Rate Qldpc  5/15 120  6/15 108  7/15 96  8/15 84  9/15 7210/15 60 11/15 48 12/15 36 13/15 24

This LDPC encoding procedure for a short FECBLOCK is in accordance witht LDPC encoding procedure for the long FECBLOCK, except replacing thetable 30 with table 31, and replacing the addresses of parity checkmatrix for the long FECBLOCK with the addresses of parity check matrixfor the short FECBLOCK.

TABLE 31 Code Rate Qldpc  5/15 30  6/15 27  7/15 24  8/15 21  9/15 1810/15 15 11/15 12 12/15 9 13/15 6

FIG. 23 illustrates a bit interleaving according to an embodiment of thepresent invention.

The outputs of the LDPC encoder are bit-interleaved, which consists ofparity interleaving followed by Quasi-Cyclic Block (QCB) interleavingand inner-group interleaving.

shows Quasi-Cyclic Block (QCB) interleaving and (b) shows inner-groupinterleaving.

The FECBLOCK may be parity interleaved. At the output of the parityinterleaving, the LDPC codeword consists of 180 adjacent QC blocks in along FECBLOCK and 45 adjacent QC blocks in a short FECBLOCK. Each QCblock in either a long or short FECBLOCK consists of 360 bits. Theparity interleaved LDPC codeword is interleaved by QCB interleaving. Theunit of QCB interleaving is a QC block. The QC blocks at the output ofparity interleaving are permutated by QCB interleaving as illustrated inFIG. 23, where Ncells=64800/η mod or 16200/η mod according to theFECBLOCK length. The QCB interleaving pattern is unique to eachcombination of modulation type and LDPC code rate.

After QCB interleaving, inner-group interleaving is performed accordingto modulation type and order (η mod) which is defined in the below table32. The number of QC blocks for one inner-group, NQCB_IG, is alsodefined.

TABLE 32 Modulation type ηmod NQCB_IG QAM-16 4 2 NUC-16 4 4 NUQ-64 6 3NUC-64 6 6 NUQ-256 8 4 NUC-256 8 8 NUQ-1024 10 5 NUC-1024 10 10

The inner-group interleaving process is performed with NQCB_IG QC blocksof the QCB interleaving output. Inner-group interleaving has a processof writing and reading the bits of the inner-group using 360 columns andNQCB_IG rows. In the write operation, the bits from the QCB interleavingoutput are written row-wise. The read operation is performed column-wiseto read out m bits from each row, where m is equal to 1 for NUC and 2for NUQ.

FIG. 24 illustrates a cell-word demultiplexing according to anembodiment of the present invention.

shows a cell-word demultiplexing for 8 and 12 bpcu MIMO and (b) shows acell-word demultiplexing for 10 bpcu MIMO.

Each cell word (c0,1, c1,1, . . . , cη mod−1,1) of the bit interleavingoutput is demultiplexed into (d1,0,m, d1,1,m . . . , d1,η mod−1,m) and(d2,0,m, d2,1,m . . . , d2,η mod−1,m) as shown in (a), which describesthe cell-word demultiplexing process for one XFECBLOCK.

For the 10 bpcu MIMO case using different types of NUQ for MIMOencoding, the Bit Interleaver for NUQ-1024 is re-used. Each cell word(c0,1, c1,1, . . . , c9,1) of the Bit Interleaver output isdemultiplexed into (d1,0,m, d1,1,m . . . , d1,3,m) and (d2,0,m, d2,1,m .. . , d2,5,m) as shown in (b).

FIG. 25 illustrates a time interleaving according to an embodiment ofthe present invention.

to (c) show examples of TI mode.

The time interleaver operates at the DP level. The parameters of timeinterleaving (TI) may be set differently for each DP.

The following parameters, which appear in part of the PLS2-STAT data,configure the TI:

DP_TI_TYPE (allowed values: 0 or 1): Represents the TI mode; ‘0’indicates the mode with multiple TI blocks (more than one TI block) perTI group. In this case, one TI group is directly mapped to one frame (nointer-frame interleaving). ‘1’ indicates the mode with only one TI blockper TI group. In this case, the TI block may be spread over more thanone frame (inter-frame interleaving).

DP_TI_LENGTH: If DP_TI_TYPE=‘0’, this parameter is the number of TIblocks NTI per TI group. For DP_TI_TYPE=‘1’, this parameter is thenumber of frames PI spread from one TI group.

DP_NUM_BLOCK_MAX (allowed values: 0 to 1023): Represents the maximumnumber of XFECBLOCKs per TI group.

DP_FRAME_INTERVAL (allowed values: 1, 2, 4, 8): Represents the number ofthe frames IJUMP between two successive frames carrying the same DP of agiven PHY profile.

DP_TI_BYPASS (allowed values: 0 or 1): If time interleaving is not usedfor a DP, this parameter is set to ‘1’. It is set to ‘0’ if timeinterleaving is used.

Additionally, the parameter DP_NUM_BLOCK from the PLS2-DYN data is usedto represent the number of XFECBLOCKs carried by one TI group of the DP.

When time interleaving is not used for a DP, the following TI group,time interleaving operation, and TI mode are not considered. However,the Delay Compensation block for the dynamic configuration informationfrom the scheduler will still be required. In each DP, the XFECBLOCKsreceived from the SSD/MIMO encoding are grouped into TI groups. That is,each TI group is a set of an integer number of XFECBLOCKs and willcontain a dynamically variable number of XFECBLOCKs. The number ofXFECBLOCKs in the TI group of index n is denoted by NxBLOCK_Group(n) andis signaled as DP_NUM_BLOCK in the PLS2-DYN data. Note thatNxBLOCK_Group(n) may vary from the minimum value of 0 to the maximumvalue NxBLOCK_Group MAX (corresponding to DP_NUM_BLOCK_MAX) of which thelargest value is 1023.

Each TI group is either mapped directly onto one frame or spread over PIframes. Each TI group is also divided into more than one TI blocks(NTI),where each TI block corresponds to one usage of time interleaver memory.The TI blocks within the TI group may contain slightly different numbersof XFECBLOCKs. If the TI group is divided into multiple TI blocks, it isdirectly mapped to only one frame. There are three options for timeinterleaving (except the extra option of skipping the time interleaving)as shown in the below table 33.

TABLE 33 Mode Description Option-1 Each TI group contains one TI blockand is mapped directly to one frame as shown in (a). This option issignaled in the PLS2-STAT by DP_TI_TYPE = ‘0’ and DP_TI_LENGTH = ‘1’(NTI = 1). Option-2 Each TI group contains one TI block and is mapped tomore than one frame. (b) shows an example, where one TI group is mappedto two frames, i.e., DP_TI_LENGTH = ‘2’ (PI = 2) and DP_FRAME_INTERVAL(IJUMP = 2). This provides greater time diversity for low data-rateservices. This option is signaled in the PLS2-STAT by DP_TI_TYPE = ‘1’.Option-3 Each TI group is divided into multiple TI blocks and is mappeddirectly to one frame as shown in (c). Each TI block may use full TImemory, so as to provide the maximum bit-rate for a DP. This option issignaled in the PLS2-STAT signaling by DP_TI_TYPE = ‘0’ and DP_TI_LENGTH= NTI, while PI = 1.

In each DP, the TI memory stores the input XFECBLOCKs (output XFECBLOCKsfrom the SSD/MIMO encoding block). Assume that input XFECBLOCKs aredefined as(d _(n,s,0,0) ,d _(n,s,0,1) , . . . ,d _(n,s,0,N) _(cells) ⁻¹ ,d_(n,s,1,0) , . . . ,d _(n,s,1,N) _(cells) ⁻¹ , . . . ,d _(n,s,N)_(xBLOCK—TI) _((n,s)−1,0) , . . . ,d _(n,s,N) _(xBLOCK—TI) _((n,s)−1,N)_(cells) ⁻¹),where d_(n,s,r,q) is the qth cell of the rth XFECBLOCK in the sth TIblock of the nth TI group and represents the outputs of SSD and MIMOencodings as follows

$d_{n,s,r,q} = \left\{ {\begin{matrix}{f_{n,s,r,q},} & {{the}\mspace{14mu}{output}\mspace{14mu}{of}\mspace{14mu}{SSD}\mspace{14mu}\ldots} & {encoding} \\{g_{n,s,r,q},} & {{the}\mspace{14mu}{output}\mspace{14mu}{of}\mspace{14mu}{MIMO}} & {encoding}\end{matrix}.} \right.$

In addition, assume that output XFECBLOCKs from the time interleaver5050 are defined as(h _(n,s,0) ,h _(n,s,1) , . . . ,h _(n,s,i) , . . . ,h _(n,s,N)_(xBLOCK—TI) _((n,s)×N) _(cells) ⁻¹)

where h_(n,s,i) is the ith output cell (for i i=0, . . . ,N_(xBLOCK)_(—) _(TI)(n,s)×N_(cells)−1) in the sth TI block of the nth TI group.

Typically, the time interleaver will also act as a buffer for DP dataprior to the process of frame building. This is achieved by means of twomemory banks for each DP. The first TI-block is written to the firstbank. The second TI-block is written to the second bank while the firstbank is being read from and so on.

The TI is a twisted row-column block interleaver. For the sth TI blockof the nth TI group, the number of rows N_(r) of a TI memory is equal tothe number of cells N_(cells), i.e., N_(r)=N_(cells) while the number ofcolumns N_(c) is equal to the number N_(xBLOCK) _(—) _(TI)(n,s).

Hereinafter, a method of deleting null packets through the null packetdeletion block using the deleted null packet indicator (DNPI) and thedeleted null packet (DNP) structure proposed by the present invention isdescribed in detail.

FIG. 26 is a diagram illustrating an example of the mode adaptationmodule of a transmission apparatus to which proposed methods may beapplied.

More specifically, FIG. 26( a) illustrates an example of an internalblock diagram of the mode adaptation module, and FIG. 26( b) illustratesan example of an internal block diagram of the null packet deletionblock of FIGS. 3 and 26( a).

Each internal block diagram of the mode adaptation module of FIGS. 3 and26( a) is operated independently, and the order of each internal blockdiagram of the mode adaptation module can be changed.

As illustrated in FIG. 26( a), the mode adaptation module may beconfigured to include at least one of pre-processing (or splitting)blocks 2610, input interface blocks 2620, input stream synchronizerblocks 2630, compensating delay blocks 2640, header compression blocks2650, null data reuse blocks 2660, null packet deletion blocks 2670, andBB frame header insertion blocks 2680.

The pre-processing block 2610 may split or demultiplex a plurality ofinput streams into a plurality of data pipes.

The pre-processing block 2610 may perform the same function as that ofthe input stream splitter of FIG. 3. Accordingly, the pre-processingblock may be represented as the input stream splitter.

In this case, the data pipe may also be called a physical layer pipe(PLP). In this case, an input stream may be a TS (MPEG2-TS), an Internetprotocol (IP) and/or a generic stream (GS). In some embodiments, aninput stream of another form is possible.

The header compression block 2650 may compress a packet header. Suchcompression may be performed in order to increase transfer efficiency ofa TS or IP input stream. Since a receiver already has priori informationabout a header, known data may be deleted from a transmitter. Forexample, information, such as a PID, may be compressed, and pieces ofinformation of other forms may be deleted or replaced. In someembodiments, the header compression block may be placed behind the nullpacket deletion block.

The null data reuse block 2660 may perform an operation for insertingnull data into a packet after header compression. The null data reuseblock 2660 may be omitted in some embodiments.

The null packet deletion block 2670 preferably may be used in the caseof a TS input stream.

Specific TS input streams or TS streams split by the pre-processingblock may include a lot of null packets in order to support variable bitrate (VBR) services in a constant bit rate (CBR) TS stream.

Accordingly, the transmission apparatus may identify null packets andmay not send the identified null packets in order to reduce overheadattributable to the transmission of unnecessary packets.

The reception apparatus accurately inserts deleted null packets intotheir original locations using a DNP counter (or DNP) with respect tothe null packets deleted by the transmission apparatus.

The null packet deletion block 2670 checks whether a null packet ispresent or not through a DNPI included in a TS packet header and insertsa DNP into the location of a deleted null packet only when a null packetis present.

As illustrated in FIG. 26( b), the null packet deletion block 2670 maybe configured to include a null packet check (sub) block 2671, a nullpacket deletion (sub) block 2672, a DNP and DNPI insertion (sub) block2673, and a null packet counter (sub) block 2674.

In this case, the term “block” may also be called as a “module” or a“unit.”

An element(s) other than the elements of FIG. 26( a) may be added to themode adaptation module of the transmission apparatus, or some of theelements of FIG. 26( a) may be omitted from the mode adaptation moduleof the transmission apparatus.

The null packet check block 2671 checks whether a corresponding packetis a null packet by analyzing the packet identifier (PID) of an input TSpacket, that is, a packet output by the null data reuse block.

If, as a result of the check, the corresponding packet is a null packet,the null packet is deleted by the null packet deletion block 2672, andthe value of a null packet counter in the null packet counter block 2674is increased by 1 whenever a null packet is deleted.

If, as a result of the check, a corresponding packet is not a nullpacket, the null packet deletion block 2672 performs no operation, andthe value of the null packet counter in the null packet counter block isreset to

In this case, the concept of the null packet counter may be the same asthat of a DNP to be described later.

The DNP and DNPI insertion block 2673 inserts a DNP ahead of a TS packetthat is transmitted after a null packet and a DNPI in TS packet headerwith reference to the value of the null packet counter of the nullpacket counter block.

That is, the DNP and DNPI insertion block 2673 generates a DNP based onthe value of the null packet counter and inserts a deleted null packetindicator (DNPI) indicative of whether a null packet is present or notin TS packet header.

As described above, the value of the null packet counter is the same asa value set in a DNP that is inserted into a location from which a nullpacket is deleted.

For example, the DNPI may be set to “1” if a null packet is present, maybe set to “0” if a null packet is not present, and may be included in aTS packet header. In this case, the setting value of the DNPI may bechanged depending on an implementation method.

FIG. 27 is a diagram illustrating an example of the mode adaptationmodule of a reception apparatus proposed by the present invention.

More specifically, FIG. 27( a) illustrates an example of an internalblock diagram of the mode adaptation module, and FIG. 27( b) illustratesan example of an internal block diagram of the null packet insertionblock of FIG. 27( a).

As illustrated in FIG. 27( a), the mode adaptation module of thereception apparatus may be configured to include at least one of BBframe header parser blocks 2710, null packet insertion blocks 2720, nulldata regenerator blocks 2730, header de-compression blocks 2740, a TSclock regeneration block 2750, de-jitter buffer blocks 2760, and a TSrecombining block 2770.

An element(s) other than the elements of FIG. 27( a) may be added to themode adaptation module of the reception apparatus, or some of theelements of FIG. 27( a) may be omitted from the elements of FIG. 27( a).

The null data regenerator block 2730 may be an element corresponding tothe null data reuse block of the transmission apparatus. The null dataregenerator block 2730 may send output to the header de-compressionblock 2740. In some embodiments, the null data regenerator block 2730may be omitted.

The header de-compression block 2740 may be an element corresponding tothe header compression block of the transmission apparatus. The headerde-compression block may restore a compressed packet header. Asdescribed above, a packet header may have been compressed in order totransfer efficiency of a TS or IP input stream. In some embodiments, theheader de-compression block 2740 may be placed ahead of the null packetinsertion block 2720.

The null packet insertion block 2720 may be placed next the BB frameheader parser block 2710. The null packet insertion block 2720accurately inserts deleted null packets into their original locationsusing a DNP counter (or a DNP) with respect to the null packets deletedby the null packet deletion block of the transmission apparatus.

As illustrated in FIG. 27( b), the null packet insertion block 2720 maybe configured to include at least one of a DNP check (sub) block 2721, anull packet insertion (sub) block 2722, and a null packet generator(sub) block 2723.

Likewise, the term “block” may also be represented as a “module” or a“unit”.

The DNP check block 2721 obtains a DNP and a DNPI from the BB frameheader parser block.

Furthermore, the DNP check block 2721 transfers the obtained DNP andDNPI to the null packet insertion block 2722.

The null packet insertion block 2722 receives a previously generatednull packet from the null packet generator block 2723 and inserts nullpackets into their original locations using the DNP and DNPI receivedfrom the DNP check block 2721.

Hereinafter, a method of indicating whether a null packet is present ornot using the error indicator of a TS packet header, proposed by thepresent invention, as a DNPI and deleting a null packet by inserting aDNP indicative of the number of null packets only when a null packet ispresent is described in detail.

First, a conventional TS packet header format and a conventional methodof deleting null packets are described with reference to FIGS. 28 and29.

FIG. 28 is a diagram illustrating an example of the conventional TSpacket header format.

As illustrated in FIG. 28, the TS packet header may be configured toinclude a transport error indicator field, a payload unit startindicator (SI) field, a transport priority (TP) field, a packetidentifier (PID) field, a scrambling control (SC) field, an adaptationfield control (AFC) field, a continuity counter (CC) field, etc.

The transport error indicator field is used as an indicator that is usedfor a reception apparatus to notify a transmission apparatus whether anerror has occurred by placing marking in the error indicator when anerror occurs in a signal after receiving the signal.

The error indicator is always set to “0” and transmitted because thetransmission apparatus assumes an error-free situation when sending asignal.

The payload unit SI field is indicative of a location where the payloadof a TS packet is started.

The TP field is indicative of the TP of a TS packet.

The PID field is indicative of an identifier

(ID) for identifying a TS packet.

FIG. 29 is a diagram illustrating an example of a conventional method ofdeleting null packets.

As illustrated in FIG. 29( a), in the conventional method of deletingnull packets, if null packets are present in a TS stream, the nullpackets are deleted, and a specific field of a specific byte size (or aspecific byte) is inserted into a location from which the null packethas been deleted in order to be indicative of the number of deleted nullpackets.

In this case, the specific field may be a deleted null packet (DNP), andthe size of the specific field may be a size of 1 byte (8 bits). If thesize of the specific field is 1 byte, a total number of null packetsthat may be deleted are 255.

The reception apparatus may restore null packets, deleted by thetransmission apparatus, through the specific field, that is, a DNP.

As illustrated in FIG. 29( b), in the conventional method of deletingnull packets, a DNP is always inserted between TS packets irrespectiveof whether a null packet is present or not. That is, a DNP is alwaysinserted between a current TS packet and a next TS packet.

That is, although a null packet is not present in a TS stream, a DNP isplaced (or inserted) ahead of a next TS packet. In this case, the DNP isset to “0.”

Furthermore, if a null packet is present in a TS stream, the null packetis deleted, and a DNP is inserted into the location of the deleted nullpacket, that is, ahead of a next TS packet. In this case, the DNP is setto a value corresponding to the number of deleted null packets.

For example, if a single null packet is deleted, a DNP is set to “1.” Iftwo null packets are deleted, a DNP is inserted into a location fromwhich the two null packets have been deleted. In this case, the DNP isset to “2.”

As described above, in the conventional method of deleting null packetsin FIG. 29, although a null packet is not present in a TS stream, a DNPof 1 byte is always added. This results in overhead in the transmissionof a TS stream.

Furthermore, as illustrated in FIG. 29, in a TS stream not includingmany null packets, DNPs of 8 bytes are added, thereby resulting greatoverhead in transmission.

That is, in FIG. 29, a DNP indicative of the number of null packets isalways inserted into a TS stream irrespective of whether a null packetis present or not in the TS stream. Accordingly, if the number of nullpackets is small, overhead is generated when a TS stream is transmitted.Furthermore, in a method of inserting a DNP only when a null packet ispresent using a separate header, overhead is also generated when a TSstream is transmitted if null packets are frequently generated.

A method of deleting null packets through a method of inserting a DNPonly when a null packet is present using the error indicator field (1bit) of a TS packet header as a DNPI, proposed by the present invention,is described in detail with reference to FIGS. 30 to 32.

FIG. 30 is a diagram illustrating an example of the format of a TSpacket header proposed by the present invention.

As illustrated in FIG. 30, the TS packet header may be configured toinclude a deleted null packet indicator (DNPI) field, a payload unitstart indicator (SI) field, a transport priority (TP) field, a packetidentifier (PID) field, a scrambling control (SC) field, an adaptationfield control (AFC) field, and a continuity counter (CC) field.

The DNPI field is indicative of whether a null packet is present or not.The DNPI field provides notification of whether a packet subsequent to(or placed behind) a TS packet including the DNPI field is a null packetand may be represented as a size of 1 bit.

For example, if the DNPI field is set to “1”, it indicates that a nullpacket is present. More specifically, it indicates that a TS packetsubsequent to a TS packet including the DNPI field is a null packet.

For another example, if the DNPI field is set to “1”, it indicates thata null packet is deleted and a DNP indicative of the number of nullpackets is inserted into a location from which the null packet has beendeleted.

If the DNPI field is set to “0”, it indicates that a null packet is notpresent. More specifically, it indicates that a TS packet subsequent toa TS packet including the DNPI field is not a null packet.

If the DNPI field is set to “0”, a DNP is not inserted.

The payload unit SI field, the TP field, the PID field, the SC field,the AFC field, and the CC field have been described with reference toFIG. 28, and thus detailed descriptions thereof are omitted.

FIG. 31 is a diagram illustrating another example of the format of a TSpacket header proposed by the present invention.

More specifically, FIG. 31 illustrates an example of the format of a TSpacket header including a DNPI field if a TS packet header iscompressed, in particular, if a PID is compressed.

The compression of a PID is applied to a case where a single data pipeDP includes a single TS packet stream.

The single TS packet stream includes the PID value of a single programmap table (PMT) packet and one or more service packets having differentPIDs.

As illustrated in FIG. 31, the TS packet header may include a DNPIfield, an SI field, a TP field, a PID-sub field, an SC field, an AFCfield, and a CC field.

The DNPI field, SI field, TP field, SC field, AFC field, and CC fieldhave been described in detail with reference to FIGS. 28 and 30, andthus detailed descriptions thereof are omitted.

The PID-sub field is indicative of a PID value after a PID field iscompressed.

For example, if the PID field is 13 bits, a PID-sub field after PIDcompression may have a size of 5 bits or 8 bits.

FIG. 32 is a diagram illustrating yet another example of the format of aTS packet header proposed by the present invention.

More specifically, FIG. 32 illustrates an example of the format of a TSpacket header including a DNPI field if the TS packet header iscompressed, in particular, if a PID is deleted.

As illustrated in FIG. 32, the TS packet header may include a DNPIfield, an SI field, a TP field, an SC field, an AFC field, and a sync.continuity counter field.

The sync. continuity counter field is indicative of a field thatreplaces the continuity counter field of FIGS. 30 and 31 due to thedeletion of a PID.

FIG. 33 is a diagram illustrating an example of a method of deletingnull packets using the DNPI field of

FIGS. 30 to 32.

A TS packet stream (or a TS stream) input as a null packet deletionblock is assumed to be that illustrated in FIG. 33( a).

In such a case, the TS packet stream of FIG. 33( a) may be output as aTS packet stream, such as that of FIG. 33( b), through the null packetdeletion block.

More specifically, each TS packet includes a DNPI field indicative ofwhether a next packet is a null packet through the null packet deletionblock.

As described above with reference to FIGS. 30 to 32, the DNPI field maybe included at a specific location of each TS packet header.

Furthermore, a null packet present in a TS packet stream is deleted, anda DNP indicative of the number of deleted null packets is inserted intoa location from which the null packet has been deleted.

The value of the DNP may be set as a value counted by the DNP counter.

As illustrated in FIG. 33( b), if the value of a DNPI field is “0”, anext packet including a DNPI corresponds to a TS packet other than anull packet. Accordingly, a DNP is not inserted because there is nodeleted null packet.

Furthermore, if the value of the DNPI field is “1”, a null packet isdeleted because a next packet including a DNPI corresponds to the nullpacket. Thus, a DNP set as a value of “1” or “2” is placed at a locationfrom which the null packet has been deleted.

In this case, if the DNP is “1”, it indicates that the number of deletednull packets is 1. If the DNP is “2”, it indicates that the number ofdeleted null packets is 2.

The structure of a DNP inserted into a location from which a null packetis deleted through the null packet deletion block proposed by thepresent invention is described in detail.

First, the structure of a conventional DNP is described with referenceto FIG. 34.

FIG. 34 is a diagram illustrating an example of the conventional DNPstructure.

As illustrated in FIG. 34, a DNP is inserted between TS packetsirrespective of whether a null packet is present or not in a TS stream.

That is, although a null packet is not present between TS packets, a DNPis inserted and the value of the inserted DNP is set to “0”.

Likewise, if a null packet is present between TS packets, a DNP isinserted and the value of the inserted DNP is set as a value indicativeof the number of (deleted) null packets.

If a TS (packet) stream includes at least one TS packet and at least onenull packet as illustrated in FIG. 34( a), it may be seen that a DNP isinserted between TS packets as illustrated in FIG. 34( b).

In this case, the DNP is composed of 8 bits, and the number of nullpackets deleted through the DNP may be represented as up to a totalnumber of 255.

If the number of deleted null packets is 256, the number of deleted nullpackets is represented as a plurality of DNP values of 255 or less usinga method of adding null packets and/or other DNPs.

As illustrated in FIG. 34( b), if the number of deleted null packets is255 or less, the number of null packets may be represented using asingle DNP.

That is, if the number of null packets is 3, a DNP has a value of “3”.If the number of null packets is 251, a DNP has a value of “251”.

It may be seen that if the number of null packets is 256 or more, atleast one DNP and/or at least one null packet is added.

That is, if the number of null packets is 520, the structure of a DNPinserted into a place from which the 520 null packets have been deletedmay be configured to (sequentially) include a first DNP having a valueof “255”, a first null packet, a second DNP having a value of “255”, asecond null packet, and a third DNP of an ‘8’ value.

As described above, if a single null packet is added as in FIG. 34, 188null bytes are transmitted.

The length of a single packet corresponds to 188 bytes.

Accordingly, an unnecessary packet of 188 bytes is transmitted due tothe transmission of an additional null packet.

In FIG. 34( a), if a TS packet stream from a TS packet 1 to a TS packet5 is transmitted, 382 bytes are additionally transmitted by the nullpacket deletion block, as illustrated in FIG. 34( b).

382 bytes=2 null packets: 376 bytes (188 bytes*2)+6 DNPs (“3”, “251”,“0”, “255”, “255”, “8”): 6 bytes

As described above, in the conventional method of deleting null packetsillustrated in FIG. 34, if the number of null packets is 255 or less,the null packets may be represented using a single DNP. If the number ofnull packets is 256 or more, however, a DNP structure must be generatedby additionally increasing at least one null packet and/or at least oneDNP.

Furthermore, although there is no null packet, a DNP having a size of 1byte has to be set to “0” and inserted between TS packets.

That is, as illustrated in FIG. 34( b), if the number of null packets is520, a DNP structure including a first DNP field indicative of 255 nullpackets, a single null packet, a second DNP indicative of 255 nullpackets, a signal null packet, and a third DNP field indicative of 8null packets may be generated in order to represent the total number of520 null packets.

A method of generating a DNP structure using two DNPs (e.g., a first DNPand a second DNP) each having a size of 1 byte in order to reduceoverhead in the transmission of a TS packet stream attributable to theaddition of unnecessary null packets and/or DNPs is described below withreference to FIGS. 35 and 36.

FIG. 35 illustrates an example of a DNP structure proposed by thepresent invention.

FIG. 35 illustrates an example of a DNP structure for representing thenumber of null packets using two DNPs, for example, a first DNP and asecond DNP.

The DNP structure may also be represented as a DNP counter structure.That is, the DNP structure may be considered to be the format of a DNPfor representing the number of null packets.

From FIG. 35( a), it may be seen that a single DNP field is used if thenumber of null packets is a specific number or less and two DNPs, thatis, a first DNP and a second DNP, are used if the number of null packetsis a specific number or more.

A value of the first DNP and/or the second DNP and a range of the valuedepending on a total number of null packets are illustrated in Table 34.

That is, Table 34 illustrates an example of a DNP structure (or a DNPcounter structure) capable of representing the number of null packetsusing a total number of 2 bytes.

TABLE 34 Number of null packets First DNP Second DNP Total DNP  0~2490~249 Not used  0~249 250~499 250 0~249 250~499 500~749 251 0~249500~749 750~999 252 0~249 750~999 1000~1249 253 0~249 1000~12491250~1499 254 0~249 1250~1499 1500~1749 255 0~249 1500~1749

From Table 34, it may be seen that a DNP has a structure capable ofusing two DNPs (i.e., a first DNP and a second DNP) depending on thenumber of null packets.

If the number of null packets is 0˜249, the null packets may berepresented using only a first DNP having a size of 1 byte.

In contrast, if the number of null packets is 250˜1749, a DNP mayrepresent the number of null packets using a first DNP and a second DNP.

That is, if the number of null packets is a specific number or more, aDNP structure includes a first DNP and a second DNP.

More specifically, if the number of null packets is 250˜499, a DNPstructure is represented using a first DNP and a second DNP, the firstDNP may be set to “250”, and the second DNP may be represented as avalue obtained by subtracting the value of the first DNP from the numberof null packets. That is, the second DNP is represented as a value of0˜249 value.

For example, if the number of null packets is 251, a DNP structuregenerated through the null packet deletion block may be representedusing a first DNP=250 and a second DNP=1.

In this case, “the first DNP=250” means that the number of null packetsstarts from 250 and a total number of null packets are represented by acombination of the value of the first DNP and the value of the secondDNP.

Furthermore, if the number of null packets is 500˜749, a DNP structureis represented using a first DNP and a second DNP, the first DNP is setto “251”, and the second DNP is represented as a value obtained bysubtracting the value of the first DNP from the number of null packets.Likewise, the second DNP may be represented in a range of 0˜249.

For example, if the number of null packets is 520, a DNP structuregenerated through the null packet deletion block may be representedusing a first DNP=251 and a second DNP=20.

In this case, “the first DNP=251” means that the number of null packetsstarts from 500 and a total number of null packets are represented by acombination of the value of the first DNP and the value of the secondDNP.

Furthermore, if the number of null packets is 750˜999, a DNP structureis represented using a first DNP and a second DNP, the first DNP is setto “252”, and the second DNP is represented as a value obtained bysubtracting the value of the first DNP from the number of null packets.Likewise, the second DNP may be represented in a range of 0˜249.

For example, if the number of null packets is 800, a DNP structuregenerated through the null packet deletion block may be representedusing a first DNP=252 and a second DNP=50.

In this case, “the first DNP=252” means that the number of null packetsstarts from 750 and a total number of null packets are represented by acombination of the value of the first DNP and the value of the secondDNP.

As illustrated in Table 34, a total number of 1749 null packets can berepresented using 2 bytes by dividing the first DNP up to 255 and thesecond DNP up to 0˜249.

Table 34 is only an example. In order to increase a total number of nullpackets that may be represented, the range of the first DNP may be setsmall or the range of the first DNP may be set great.

FIG. 36 is a diagram illustrating an example of a method of deletingnull packets using the DNP structure of FIG. 35.

FIG. 36( a) illustrates a TS packet stream including at least one TSpackets and at least one null packet, and FIG. 36( b) illustrates a TSpacket stream, that is, a result of the TS packet stream of FIG. 36( a)output through the null packet deletion module.

From FIG. 36( b), it may be seen that each TS packet includes a DNPIfield, the DNPI field has a value of “1” if a TS packet subsequent to aTS packet is a null packet, and the DNPI field has a value of “0” if aTS packet subsequent to a TS packet is a TS packet other than a nullpacket.

It may also be seen that a DNP structure has one or two DNPs at alocation from which null packets have been deleted through the DNPstructure of Table 34.

Referring to FIG. 36( b), if the number of null packets is 3, itcorresponds to the case where the number of null packets is 250 or lessin Table 34. Accordingly, the number of null packets may be representedusing only a first DNP (i.e., the first DNP=3).

Furthermore, if the number of null packets is 251, it corresponds to thecase where the number of null packets is 250˜499 in Table 34.Accordingly, the number of null packets may be represented using a firstDNP (=250) and a second DNP (=1).

Furthermore, if the number of null packets is 520, it corresponds to thecase where the number of null packets is 500˜749 in Table 34.Accordingly, the number of null packets may be represented using a firstDNP (=251) and a second DNP (=20).

Furthermore, if the number of null packets is 800, it corresponds to thecase where the number of null packets is 750˜999 in Table 34.Accordingly, the number of null packets may be represented using a firstDNP (=252) and a second DNP (=60).

As described above, if the number of null packets is represented usingthe conventional method of FIG. 34, 382 bytes are additionally required.If the number of null packets is represented using the method of FIGS.35 and 36 proposed by the present invention, however, the same functioncan be performed by adding only 5 bytes.

The aforementioned DNP structures depending on the number of nullpackets are illustrated in Table 35.

TABLE 35 Number of null packets First DNP Second DNP Total DNP 3 3 — 3251 250 1 250 + 1 = 251 520 251 20 500 + 20 = 520 800 252 50 750 + 50 =800

The present invention may be applied to a method and apparatus forreceiving and sending broadcast signals.

Both the apparatus and method inventions described in the presentinvention and the descriptions of both the apparatus and methodinventions may be complementarily applicable to each other.

It will be appreciated by those skilled in the art that variousmodifications and variations may be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A method for transmitting a broadcast signal,comprising: formatting input stream into one or more physical layerpipes (PLPs); encoding data of the one or more PLPs; generating at leastone signal frame by mapping the encoded data; and modulating the atleast one signal frame using an orthogonal frequency divisionmultiplexing (OFDM) scheme and transmitting the broadcast signalcomprising the at least one modulated signal frame, wherein the inputstream comprises multiple packets, wherein the multiple packets compriseat least one of a null packet or a data packet, wherein the null packetincluded in the input stream is deleted, wherein a number of the deletednull packet is counted, wherein a deleted null packet (DNP) field isinserted into a location which the null packet has been deleted, andwherein the deleted null packet (DNP) field is an information indicatingthe number of the deleted null packet.
 2. The method of claim 1, whereinthe DNP field inserted into the location which the null packet has beendeleted is set as the counted value.
 3. The method of claim 1, whereinthe input stream comprises a deleted null packet indicator (DNPI) fieldindicative of whether or not a next packet is a null packet.
 4. Themethod of claim 3, wherein if the DNPI field is set as a valueindicating that a next packet is a null packet, the DNP field isinserted into a data packet subsequent to a data packet comprising theDNPI field.
 5. The method of claim 3, wherein a header of the datapacket is generated by compressing a packet identifier (PID) or deletingthe PID.
 6. The method of claim 5, wherein: the DNPI field is includedin the header of the data packet.
 7. The method of claim 1, wherein: theDNP field comprises at least one of a first DNP or a second DNP.
 8. Themethod of claim 7, wherein: the DNP field comprises only the first DNPif the number of the deleted null packet is a specific number or less,and the DNP field comprises the first DNP and the second DNP if thenumber of the deleted null packet is a specific number or more.
 9. Themethod of claim 8, wherein: the first DNP is set as a specific valueindicative of a specific number of null packets if the first DNP and thesecond DNP are included in the DNP field, and the second DNP is set as avalue obtained by subtracting the value of the first DNP from a totalnumber of deleted null packets.
 10. The method of claim 7, wherein thesecond DNP is placed next to the first DNP.
 11. The method of claim 1,wherein the data packet is a TS(Transport Stream) packet.
 12. Atransmission apparatus for transmitting a broadcast signal, comprising:an input formatting module configured to format input stream into one ormore physical layer pipes (PLPs); a bit interleaved coding andmodulation (BICM) module configured to encode data of the one or morePLPs; a frame building module configured to generate at least one signalframe by mapping the encoded data; and an orthogonal frequency divisionmultiplexing (OFDM) generation module configured to modulate the atleast one signal frame using an OFDM scheme and transmit the broadcastsignal comprising the at least one modulated signal frame, wherein theinput stream comprises multiple packets, wherein the multiple packetscomprise at least one of a null packet or a data packet, wherein thetransmission apparatus further comprising: a null packet deletion moduleconfigured to delete the null packet included in the input stream; andwherein the transmission apparatus comprises a DNP insertion moduleconfigured to insert a deleted null packet (DNP) field into a locationfrom which the null packet has been deleted, wherein a number of thedeleted null packet is counted, wherein the deleted null packet (DNP)field is an information indicating the number of the deleted nullpacket.
 13. The transmission apparatus of claim 12, wherein thetransmission apparatus further comprises: a null packet counter moduleconfigured to count the number of the deleted null packet.
 14. Thetransmission apparatus of claim 12, wherein: the input stream comprisesa header of the data packet comprises a deleted null packet indicator(DNPI) field indicating whether a next packet is a null packet.
 15. Areceiving apparatus for receiving broadcast signals, the apparatuscomprising: a demapping and decoding module; and an output processormodule restoring one or more physical layer pipes (PLPs) output from thedemapping and decoding module to input stream, wherein the outputprocessor module includes a baseband frame processor block decodinginformation transmitted to a header of a baseband frame and restoringthe input stream by using the decoded information, wherein the inputstream comprises multiple packets, wherein the multiple packets compriseat least one of a null packet or a data packet, wherein the null packetincluded in the input stream is deleted, wherein a number of the deletednull packet is counted, wherein a deleted null packet (DNP) field isinserted into a location which the null packet has been deleted, andwherein the deleted null packet (DNP) field is an information indicatingthe number of the deleted null packet.